Patent Application
20120141831
The present invention relates to a multilayer transparent light-receiving device and an electronic device, and in particular, relates to a multilayer transparent light-receiving device using a protein and various electronic devices such as a three dimensional display, a three dimensional image sensor, and a camera using the multilayer transparent light-receiving device as a light detector or the like.
In the past, a CCD, a CMOS and the like have been mainly used as a light-receiving device. However, since the CCD, the CMOS and the like are structured based on silicon semiconductor technology, the light-receiving device itself has not been transparent. Thus, most stereoscopic view cameras using the foregoing existing light-receiving devices use binocular parallax simulating mechanism similar to human eyes (for example, a stereo camera or the like). However, by using such mechanism, two or more cameras should be connected, and the structure becomes complicated. Further, two or more lenses should be prepared naturally, and thus it is difficult to downsize the cameras. Further, since one eye is available for one focus of an image pickup section, it has not be possible to obtain a picture in which various objects are focused on concurrently. Further, in the case where a near place is captured immediately after a state that a significantly far place is focused on, since one eye is available for only one focus, the lens should be moved largely for focusing at high velocities, which limits ability for focusing at extremely high speeds.
Meanwhile, in optical disc systems, optical discs have been progressively multilayered, which contributes to significant improvement of the recording capacity. However, in the foregoing existing light-receiving device, it is not possible to achieve a multilayered light-receiving device for light detection in the optical disc system, which is an obstacle in the way of development of the optical disc system using the multilayered optical disc.
In the past, a light transmissive image recognition device capable of transmitting an inputted image has been proposed (see Patent document 1). The light transmissive image recognition device includes a first transparent substrate in which a plurality of transparent pixel electrodes are formed on the surface two dimensionally, a second transparent substrate in which a transparent opposed electrode is formed on the surface, and a visual substance analogous protein orientation alignment film layer and a transparent insulating layer arranged between both electrodes. As the visual substance analogous protein orientation alignment film layer, a bacteriorhodopsin orientation alignment film layer is used.
In addition, as a photoelectric conversion element using a protein, a photoelectric conversion device using a protein immobilized electrode in which zinc-substituted horse heart cytochrome c (obtained by substituting iron as a central metal of prosthetic group heme of horse heart cytochrome c with zinc) is immobilized onto a gold electrode has been proposed (see Patent document 2). In addition, it is disclosed that a photocurrent is obtained by the protein immobilized electrode.
However, in the light transmissive image recognition device proposed in Patent document 1, when an image is projected from the first transparent substrate side onto the visual substance analogous protein orientation alignment film layer, an induction current induced to the pixel electrode by electric polarization of the visual substance analogous protein orientation alignment film layer is detected. Thus, the photoresponsive speed is slow, and in addition, since Langmuir Blodgett method is used for forming the visual substance analogous protein orientation alignment film layer, productivity is not favorable. Further, in Patent document 1, detection of the induction current induced to the pixel electrode by electric polarization of the visual substance analogous protein orientation alignment film layer is not verified at all.
Therefore, the problems to be solved by the present invention are to provide a multilayer transparent light-receiving device with significantly high photoresponsive speed and being easily manufactured, and a high-performance electronic device using the multilayer transparent light-receiving device.
To solve the foregoing problems, in the present invention, there is provided a multilayer transparent light-receiving device that has a plurality of protein transparent light-receiving elements laminated on each other using an electron transfer protein.
Further, in the present invention, there is provided an electronic device that includes a multilayer transparent light-receiving device that has a plurality of protein transparent light-receiving elements laminated on each other using an electron transfer protein.
In the present invention, as the electron transfer protein, existing known electron transfer proteins are able to be used. More specifically, as the electron transfer protein, an electron transfer protein containing a metal or an electron transfer protein not containing a metal (metal free electron transfer protein) is able to be used. The metal contained in the electron transfer protein is suitably a transition metal having electrons in a high energy orbit equal to or greater than d orbit (for example, zinc, iron or the like). As the electron transfer protein, a new electron transfer protein described later is able to be used.
The electron transfer protein is typically immobilized onto a transparent electrode made of a material transparent to light to be received, typically visible light. In a typical example, the protein transparent light-receiving element has a protein immobilized electrode in which the electron transfer protein is immobilized onto the transparent electrode and a counter electrode. In another typical example, the protein transparent light-receiving element has a structure in which a solid protein layer composed of the electron transfer protein is sandwiched between a first transparent electrode and a second transparent electrode. As a material of the transparent electrode, both an inorganic material and an organic material may be used, and the material is selected according to needs.
As the electronic device, any type may be applicable as long as the multilayer transparent light-receiving device is able to be used. Specific examples thereof include a three dimensional display, a three dimensional image sensor, a camera, and an optical recording reproduction system.
In the present invention configured as above, the electron transfer protein has higher photoresponsive speed than a visual substance analogous protein such as bacteriorhodopsin. In addition, for example, by coating the transparent electrode with a solution containing the electron transfer protein, the protein immobilized electrode is able to be more easily fabricated.
According to the present invention, a multilayer transparent light-receiving device that has significantly high photoresponsive speed and that is easily manufactured is able to be achieved. Further, by using such a superior multilayer transparent light-receiving device, a high performance electronic device is able to be achieved.
Embodiments for carrying out the present invention (hereinafter referred to as “embodiment”) will be hereinafter described. In addition, the description will be given in the following order.
1. First embodiment (multilayer transparent light-receiving device)
2. Second embodiment (multilayer transparent light-receiving device)
3. Third embodiment (multilayer transparent light-receiving device)
4. Fourth embodiment (multilayer transparent light-receiving device)
5. Fifth embodiment (multilayer transparent light-receiving device)
6. Sixth embodiment (multilayer transparent light-receiving device)
7. Seventh embodiment (stereoscopic imaging system)
8. Eighth embodiment (stereoscopic imaging system)
9. Ninth embodiment (stereoscopic imaging system)
10. Tenth embodiment (optical disc system)
11. Eleventh embodiment (optical recording reproduction system)
As illustrated in
As illustrated in
In
As a material of the transparent substrate 11, for example, various inorganic or organic transparent materials such as glass, mica, and polyethylene terephthalate (PET) are able to be used.
As a material of the transparent electrode 12, a transparent metal oxide such as ITO (indium-tin composite oxide), FTO (fluorine-doped tin oxide), and NESA glass (SnO2 glass), an extremely thin metal film capable of transmitting light such as a Au film and the like are able to be used.
As an electron transfer protein of the electron transfer protein layer 13, specifically, for example, cytochromes, iron-sulfur proteins, blue-copper proteins and the like are able to be used. Examples of the cytochromes include cytochrome c (zinc-substituted cytochrome c, metal free cytochrome c and the like), cytochrome b, cytochrome b5, cytochrome c1, cytochrome a, cytochrome a3, cytochrome f, and cytochrome b6. Examples of the iron-sulfur proteins include rubredoxin, two-iron ferredoxin, three-iron ferredoxin, and four-iron ferredoxin. Examples of the blue-copper proteins include plastocyanin, azurin, pseudo azurin, plantacyanin, steracyanin, and amicyanin. The electron transfer protein is not limited thereto. For example, a derivative of the foregoing electron transfer proteins (obtained by chemically modifying an amino-acid residue of a skeleton) or a variant thereof (obtained by substituting part of an amino-acid residue of a skeleton with other amino-acid residue) is able to be used. These electron transfer proteins are all water-soluble proteins.
The protein transparent light-receiving element 1 is able to be operated both in a solution (electrolyte solution) and in dry environment as long as photoelectric conversion function and electron transfer function of the electron transfer protein of the electron transfer protein layer 13 are not impaired. In other words, the electrolyte layer 14 may be composed of an electrolyte solution or a solid electrolyte. As an electrolyte of the electrolyte layer 14 (or redox species), an electrolyte with which oxidation reaction is initiated in the protein immobilized electrode in which the electron transfer protein layer 13 is immobilized onto the transparent electrode 12 and reduction reaction is initiated in the transparent counter electrode 15, or an electrolyte with which reduction reaction is initiated in the foregoing protein immobilized electrode and oxidation reaction is initiated in the transparent counter electrode 15 is used. Specifically, as the electrolyte, for example, K4[Fe(CN)6], [Co(NH3)6]Cl3 or the like is used. In the case where the protein transparent light-receiving element 1 is operated in dry environment, typically, for example, the electrolyte layer 14 composed of a solid electrolyte not absorbing the electron transfer protein, specifically the electrolyte layer 14 composed of a wet solid electrolyte such as agar and polyacrylamide gel is sandwiched between the protein immobilized electrode and the transparent counter electrode 15, and the surrounding thereof is provided with a sealing wall to prevent the solid electrolyte from being dried. In these cases, a photocurrent is able to be obtained in the case where light is received at a light receiving section composed of the electron transfer protein layer 13 under polarity based on natural electrode potential difference between the protein immobilized electrode and the transparent counter electrode 15.
As a material of the transparent counter electrode 15, a transparent metal oxide such as ITO, FTO, and NESA glass, an extremely thin metal film capable of transmitting light such as a Au film and the like are able to be used.
As illustrated in
For performing photoelectric conversion by the protein transparent light-receiving element 1, the electron transfer protein layer 13 of the protein immobilized electrode is irradiated with light in a state that a bias voltage is applied to the protein immobilized electrode with reference to a transparent reference electrode 18 by a bias power source 17. The light is monochromatic light capable of light excitation of the electron transfer protein of the electron transfer protein layer 13 or light having an element of such light. In this case, by adjusting at least one of the bias voltage applied to the protein immobilized electrode, the intensity of the irradiated light, and the wavelength of the irradiated light, the magnitude and/or the polarity of a photocurrent flown through the device is able to be changed. The photocurrent is extracted outside from terminals 19a and 19b.
As illustrated in
As illustrated in
[Manufacturing Method of Multilayer Transparent Light-Receiving Device]
A description will be given of an example of a manufacturing method of the multilayer transparent light-receiving device.
First, the transparent electrode 12 formed on the transparent substrate 11 is soaked in a solution containing an electron transfer protein and a buffer solution, and thereby the electron transfer protein is immobilized onto the transparent electrode 12. Thus, the protein immobilized electrode in which the electron transfer protein layer 13 is formed on the transparent electrode 12 is formed.
Next, by using the protein immobilized electrode and the transparent counter electrode 15, the protein transparent light-receiving element 1 illustrated in, for example,
After that, the necessary number of the protein transparent light-receiving devices 1 are laminated. At this time, the respective protein transparent light-receiving devices 1 are bonded by a transparent adhesive or the like according to needs.
[Operation of Multilayer Transparent Light-Receiving Device]
When monochromatic light in wavelength corresponding to the electron transfer protein of the electron transfer protein layer 13 or light including the wavelength component enters the electron transfer protein layer 13 of the respective protein transparent light-receiving devices 1 of the multilayer transparent light-receiving device, electrons are generated from the electron transfer protein of the electron transfer protein layer 13 due to light excitation, and the electrons are moved to the transparent electrode 12 due to electron transfer. In the result, a photocurrent is extracted outside from the transparent electrode 12 and the transparent counter electrode 15.
According to the first embodiment, the multilayer transparent light-receiving device in which the plurality of protein transparent light-receiving devices 1 using the electron transfer protein are laminated is able to be achieved.
The multilayer transparent light-receiving device is able to be used for various apparatuses, devices and the like that use photoelectric conversion. Specifically, the multilayer transparent light-receiving device is able to be used for an electronic device having a light receiving section and the like. Such an electronic device may be any type fundamentally, and includes a portable type and a stationary type. For example, as will be described later, a camera capable of concurrently focusing on a plurality of objects located in a position different from each other by using one lens is able to be achieved. It shows that the camera is able to obtain information reproducing a three dimensional picture at once with the use of a single lens, which enables realizing a simpler and downsized stereo camera. Further, by using the multilayer transparent light-receiving device, multifocusing and high-speed focusing with the use of a single lens are enabled. Further, in the case where the multilayer transparent light-receiving device is used as a light-receiving device of an optical disc system using a multilayer optical disc or an optical recording reproduction system using a holographic recording medium, parallel readout of the multilayer optical disc and readout of the holographic recording medium are able to be easily performed.
A multilayer transparent light-receiving device according to a second embodiment has a structure similar to that of the multilayer transparent light-receiving device according to the first embodiment, except that a new electron transfer protein is used as an electron transfer protein of the electron transfer protein layer 13 of the protein transparent light-receiving element 1.
The new electron transfer protein is tin-substituted cytochrome c obtained by substituting iron as a central metal of heme of mammal-derived cytochrome c with tin, or a protein that is composed of an amino-acid sequence obtained by losing, substituting, or adding one or several amino acids in an amino-acid sequence of the mammal-derived cytochrome c and that contains tin. Here, examples of the mammal-derived cytochrome c include horse heart cytochrome c and bovine heart cytochrome c. These new electron transfer proteins have significantly high stability to light irradiation, and are able to retain photoelectric conversion function for a long time.
A description will be given of details and a preparation method of the tin-substituted cytochrome c.
<Tin-Substituted Cytochrome c>
Table 1 illustrates amino-acid sequences (one letter symbols) of the horse heart cytochrome c (described as CYC HORSE) and the bovine heart cytochrome c (described as CYC BOVIN). As illustrated in Table 1, the horse heart cytochrome c and the bovine heart cytochrome c have the same structure except for three residues out of all 104 amino acid residues. In the bovine heart cytochrome c, Thr48, Lys61, and Thr90 of the horse heart cytochrome c are respectively substituted with Ser48, Gly61, and Gly90.
KEETLMEYLENPKKYIPGTKMIFAGIKKKT
GEETLMEYLENPKKYIPGTKMIFAGIKKKG
It has been known that the bovine heart cytochrome c has higher stability of the protein portion to heat and a denaturant (guanidine hydrochloride) than the horse heart cytochrome c (Nonpatent documents 1 and 2). Table 2 illustrates denaturation midpoint temperature T1/2 and denaturation midpoint concentration [Gdn-HCl]1/2 of the horse heart cytochrome c and the bovine heart cytochrome c. The denaturation midpoint temperature T1/2 is the temperature at which the ratio occupied by a denatured protein out of all proteins in the system becomes half (½). Further, the denaturation midpoint concentration [Gdn-HCl]1/2 is the concentration of guanidine hydrochloride (Gdn-HCl) at which the ratio occupied by the denatured protein out of all proteins in the system becomes half (½). As numerical values of T1/2 and [Gdn-HCl]1/2 are higher, it is more stable.
<Preparation of the Tin-Substituted Cytochrome c>
The tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c were prepared as described below. For comparative experiment, zinc-substituted horse heart cytochrome c and zinc-substituted bovine heart cytochrome c were also prepared.
The horse heart cytochrome c and the bovine heart cytochrome c made by Sigma Corporation were used.
A description will be mainly given of a preparation method of the tin-substituted horse heart cytochrome c. However, preparation methods of the tin-substituted bovine heart cytochrome c, the zinc-substituted horse heart cytochrome c, and the zinc-substituted bovine heart cytochrome c are similar to the preparation method of the tin-substituted horse heart cytochrome c. In addition, the protein that is composed of the amino-acid sequence obtained by losing, substituting, or adding one or several amino acids in the amino-acid sequence of the horse heart cytochrome c or the bovine heart cytochrome c and that contains tin is also able to be similarly prepared by using a technique such as random mutation and chemical modification as appropriate.
6 mL of 70% fluorinated acid/pyridine was added to 100 mg of horse heart cytochrome c powder, and the resultant was incubated for 10 minutes at room temperature. Thereby, iron as a central metal of heme was removed from the horse heart cytochrome c. 9 mL of 50 mM ammonium acetate buffer solution (pH5.0) was added to the horse heart cytochrome c from which iron was removed as described above. After reaction stop, a metal free horse heart cytochrome c from which the central metal was removed was obtained by gel filtration column chromatography (column volume: 150 mL, resin: Sephadex G-50, developing solvent: 50 mM sodium acetate buffer solution (pH5.0)).
The metal free horse heart cytochrome c solution was condensed as much as possible, and the resultant was added with glacial acetic acid to obtain ph2.5 (±0.05). The obtained solution was added with about 25 mg of tin chloride powder, and the resultant was incubated for 30 minutes at 50 deg C. under light shielding. In the foregoing process, if zinc acetate or zinc chloride was added instead of tin chloride, a zinc-substituted product was obtained. Ultraviolet visible absorption spectrum was measured every 10 minutes. Until a ratio between absorption peak in wavelength 280 nm of protein and absorption peak in wavelength 408 nm derived from tin porphyrin became constant, incubation was continued.
All operations on and after the foregoing process were performed under light shielding. After the foregoing finally obtained solution was added with saturated diphosphoric acid-sodium hydrogen solution to obtain neutral pH (6.0<), buffer solution exchange to 10 mM sodium phosphate buffer solution (pH 7.0) was performed. After that, a monomeric fraction was collected by cation exchange column chromatography (column volume: 40 mL, resin: SP-Sephadex Fast Flow, elution: linear concentration gradient of 10 to 150 mM sodium phosphate buffer solution (pH 7.0)). Accordingly, the tin-substituted horse heart cytochrome c was prepared.
Measurement results of the tin-substituted horse heart cytochrome c, the tin-substituted bovine heart cytochrome c, the zinc-substituted horse heart cytochrome c, and the zinc-substituted bovine heart cytochrome c prepared as described above are illustrated in
<Light Irradiation Degradation Experiment of the Metal Substitution Cytochromes c>
Light irradiation degradation experiment of the foregoing four types of metal substitution cytochromes c, that is, the tin-substituted horse heart cytochrome c, the tin-substituted bovine heart cytochrome c, the zinc-substituted horse heart cytochrome c, and the zinc-substituted bovine heart cytochrome c was performed as follows.
1 mL of about 4 μM metal substitution cytochrome c (dissolved in 10 mM sodium phosphate buffer solution (pH 7.0)) was set in a cuvette. The zinc-substituted product was irradiated with light in wavelength 420 nm (intensity: 1255 μW), and the tin-substituted product was irradiated with light in wavelength 408 nm (intensity: 1132 μW) in a dark room at room temperature. Ultraviolet visible absorption spectrum in wavelengths from 240 to 700 nm both inclusive was measured every 30 minutes. The results thereof are illustrated in
From
From the average of two experiments, the photodegrative rate constant k of the foregoing four types of metal substitution cytochromes c was obtained. In the result, the photodegrative rate constant k of the tin-substituted horse heart cytochrome c was 1.39±0.13 M−1 s−1, the photodegrative rate constant k of the tin-substituted bovine heart cytochrome c was 0.90±0.20 M−1 s−1, the photodegrative rate constant k of the zinc-substituted horse heart cytochrome c was 67.2±1.4 M−1 s−1, and the photodegrative rate constant k of the zinc-substituted bovine heart cytochrome c was 56.1±1.0 M−1 s−1. From the results, it was found that light degradation rates of both the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c were 50 to 60 times slower than those of the zinc-substituted horse heart cytochrome c and the zinc-substituted bovine heart cytochrome c, which meant that both the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c were significantly stable to light irradiation. Further, it was found that both for the zinc-substituted product and the tin-substituted product, light degradation rate of the bovine heart cytochrome c was 1.2 to 1.5 times slower than that of the horse heart cytochrome c, which meant that the bovine heart cytochrome c was stable to light irradiation. In particular, the tin-substituted bovine heart cytochrome c was stable to light irradiation 75 times as much as the zinc-substituted horse heart cytochrome c used in Patent document 1.
<Photocurrent Generation Experiment of the Metal Substitution Cytochromes c>
A protein immobilized electrode used for photocurrent generation experiment was fabricated as follows.
As illustrated in
The protein immobilized electrode was soaked in 27 mL of 10 mM sodium phosphate buffer solution (pH 7.0) containing 0.25 mM potassium ferrocyanide, platinum mesh was used as a counter electrode, a silver/silver chloride electrode was used as a reference electrode, the photocurrent measurement apparatus illustrated in FIG. 4 of Patent document 2 was used, electric potential to the silver/silver chloride electrode was 120 mV, and thereby photocurrent action spectrum in wavelengths from 380 to 600 nm was measured. In the measurement, standby time was 900 sec, measurement time was 60 sec, current range was 10 nA, filter frequency was 30 Hz, and time resolution was 50 mS. For the four types of metal substitution cytochromes c, five electrodes were respectively formed and the measurement was performed.
Obtained photocurrent action spectrums are illustrated in
<Fluorescence Quantum Efficiency of the Metal Substitution Cytochromes c>
Diluent solutions with different concentrations of the metal substitution cytochrome c were prepared. Ultraviolet visible absorption spectrums in wavelengths from 380 to 440 nm both inclusive and fluorescent spectrums in wavelengths from 500 to 700 nm both inclusive (excitation wavelength: 409 nm) were measured. The results thereof are illustrated in
As illustrated in
As described above, stability to light irradiation of both the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c was significantly higher than stability to light irradiation of the zinc-substituted horse heart cytochrome c and the zinc-substituted bovine heart cytochrome c. Thus, by using the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c, the new protein transparent light-receiving element 1 capable of being stably used for a long time is able to be achieved. The protein transparent light-receiving element 1 is able to be used for a light sensor and an image pickup device. Further, in both the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c, light absorption maximum wavelength is 409 nm, which is close to wavelength 405 nm of laser diodes currently used for optical disc systems available for high density recording. Thus, for example, by using a medium in which the tin-substituted horse heart cytochrome c or the tin-substituted bovine heart cytochrome c is bedded on a substrate instead of an optical disc, a new memory is able to be achieved. Further, since the diameter of the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c is significantly small, about 2 nm, the number of devices capable of being mounted per unit area of a substrate is able to be significantly increased compared to that in the past. Therefore, a high definition light sensor, a high definition image pickup device and the like are able to be achieved, or a large capacity memory is able to be achieved.
[Manufacturing Method of Multilayer Transparent Light-Receiving Device]
A description will be given of an example of a manufacturing method of the multilayer transparent light-receiving device.
First, the transparent electrode 12 formed on the transparent substrate 11 is soaked in a solution containing an electron transfer protein and a buffer solution, and thereby the electron transfer protein is immobilized onto the transparent electrode 12. Accordingly, the protein immobilized electrode in which the electron transfer protein layer 13 is formed on the transparent electrode 12 is formed.
Next, by using the protein immobilized electrode and the transparent counter electrode 15, the protein transparent light-receiving element 1 illustrated in, for example,
After that, the necessary number of the protein transparent light-receiving devices 1 are laminated. At this time, the respective protein light-receiving devices 1 are bonded to each other by a transparent adhesive or the like according to needs.
[Operation of Multilayer Transparent Light-Receiving Device]
When monochromatic light of wavelength (for example, about 409 m) corresponding to the electron transfer protein of the electron transfer protein layer 13 or light including the wavelength component enters the electron transfer protein layer 13 of the respective protein transparent light-receiving devices 1 of the multilayer transparent light-receiving device, electrons are generated from the electron transfer protein of the electron transfer protein layer 13 due to light excitation, and the electrons are moved to the transparent electrode 12 by electron transfer. In the result, a photocurrent is extracted outside from the transparent electrode 12 and the transparent counter electrode 15.
As described above, according to the second embodiment, the electron transfer protein layer 13 composed of the tin-substituted horse heart cytochrome c or the tin-substituted bovine heart cytochrome c having high light irradiation stability is immobilized onto the transparent electrode 12. Thus, even if light is irradiated for a long time, the electron transfer protein layer 13 is not deteriorated, and the new protein transparent light-receiving element 1 capable of being used stably for a long time, that is, the multilayer transparent light-receiving device is able to be achieved.
In the same manner as the multilayer transparent light-receiving device according to the first embodiment, the multilayer transparent light-receiving device is able to be used for various apparatus, devices and the like that use photoelectric conversion. Specifically, for example, the multilayer transparent light-receiving device is able to be used for an electronic device having a light receiving section and the like.
For example, as will be described later, a camera capable of concurrently focusing on a plurality of objects located in a position different from each other by using one lens is able to be achieved. Further, by using the multilayer transparent light-receiving device, multifocusing and high-speed focusing with the use of a single lens are enabled. Further, in the case where the multilayer transparent light-receiving device is used as a light-receiving device of an optical disc system using a multilayer optical disc or an optical recording reproduction system using a holographic recording medium, parallel readout of the multilayer optical disc and readout of the holographic recording medium are able to be easily performed.
A multilayer transparent light-receiving device according to a third embodiment has a structure similar to that of the multilayer transparent light-receiving device according to the first embodiment, except that a new electron transfer protein is used as an electron transfer protein of the electron transfer protein layer 13 of the protein transparent light-receiving element 1.
The new electron transfer protein is composed of metal substitution cytochrome c obtained by substituting iron as a central metal of heme of mammal-derived cytochrome c with a metal other than zinc and tin whose fluorescent excitation life τ is 5.0×10−11 s<τ≦8.0×10-10 s, or a protein that is composed of an amino-acid sequence obtained by losing, substituting, or adding one or several amino acids in an amino-acid sequence of the mammal-derived cytochrome c and that contains a metal other than zinc and tin whose fluorescent excitation life τ is 5.0×10−11 s<τ≦8.0×10−10 s. Examples of the mammal-derived cytochrome c include the horse heart cytochrome c and the bovine heart cytochrome c. These new electron transfer proteins have significantly high stability to light irradiation, and are able to retain photoelectric conversion function for a long time.
<Metal Substitution Cytochrome c>
A description will be given of metal substitution horse heart cytochrome c and metal substitution bovine heart cytochrome c obtained by substituting iron as a central metal of heme of the horse heart cytochrome c and the bovine heart cytochrome c with a metal other than tin and zinc.
Examples of metals used for the metal substitution horse heart cytochrome c and the metal substitution bovine heart cytochrome c are illustrated in Table 4. It has been known that porphyrins containing these metals as a central metal generate fluorescence (Nonpatent document 5). In Table 4, the numerical values described under the respective atomic symbols indicate each phosphorescence life measured for metal octaethylporphyrins.
As illustrated in Table 4, the phosphorescence life of tin (Sn) porphyrin is 30 ms. Metal porphyrins whose phosphorescence life is equal to or shorter than the phosphorescence life of tin (Sn) porphyrin possibly do not damage a protein or a porphyrin ring section due to light irradiation. As illustrated in Table 4, such metals include beryllium (Be), strontium (Sr), niobium (Nb), barium (Ba), lutetium (Lu), hafnium (Hf), tantalum (Ta), cadmium (Cd), antimony (Sb), thorium (Th), and lead (Pb).
The iron as a central metal of heme of the horse heart cytochrome c and the bovine heart cytochrome c is substituted with these metals. For such substitution, a method similar to that described in the second embodiment is able to be used.
In the metal substitution horse heart cytochrome c and the metal substitution bovine heart cytochrome c obtained as above, it is stable to light irradiation as in the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c, and light degradation is hardly generated.
Here, a description will be given of fluorescent excitation life range needed for the metal substitution horse heart cytochrome c and the metal substitution bovine heart cytochrome c.
Intramolecular hole transfer rate of the zinc-substituted horse heart cytochrome c (Nonpatent document 4) is as follows. When molecular orbital numbers in accordance with Nonpatent document 4 are used as a molecular orbital (MO) number, the intramolecular hole transfer rate of the zinc-substituted horse heart cytochrome c is 1.5×1011 s−1 in transition between MO3272 and MO03271, and is 2.0×1010 s−1 in transition between MO3268 and MO3270. In this case, the lower limit of the intramolecular hole transfer rate is set to the latter value, 2.0×1010 s−1.
Fluorescent excitation life of the tin-substituted horse heart cytochrome c (Nonpatent document 3) is 8.0×10−10 s. Fluorescent excitation life of the zinc-substituted horse heart cytochrome c is 3.2×10−10 s.
The number of intramolecular hole transfers one electron excitation of the tin-substituted horse heart cytochrome c is (1.5×1011 s−1)×(8.0×10−10 s)=120 in transition between MO03272 and MO03271, and (2.0×1010 s−1)×(8.0×10−10 s)=16 in transition between MO03268 and MO03270. In this case, the lower limit of the number of intramolecular hole transfers in one electron excitation is set to the latter value, 16.
In this case, fluorescent excitation life needed for generating at least one hole transfer is 8.0×10−10 s/16=5.0×10−11 s.
Accordingly, fluorescent excitation life (T) range of the metal substitution horse heart cytochrome c and the metal substitution bovine heart cytochrome c that does not damage a protein portion or porphyrin due to light irradiation and that is needed for generating hole transfer is 5.0×10−11 s (fluorescent excitation life needed for generating at least one hole transfer)<τ≦8.0×10−10 s (fluorescent excitation life of the tin-substituted horse heart cytochrome c).
According to the third embodiment, the metal substitution horse heart cytochrome c or the metal substitution bovine heart cytochrome c is used as an electron transfer protein of the electron transfer protein layer 13 of the protein transparent light-receiving element 1. Thereby, advantages similar to those of the multilayer transparent light-receiving device according to the second embodiment using the tin-substituted horse heart cytochrome c and the tin-substituted bovine heart cytochrome c are able to be obtained.
A multilayer transparent light-receiving device according to a fourth embodiment has a structure similar to that of the multilayer transparent light-receiving device according to the first embodiment, except that a solid protein layer composed of an electron transfer protein as the electron transfer protein layer 13 of the protein transparent light-receiving element 1 is used.
As illustrated in
An example of a structure in the case that the solid protein layer 43 is composed of a multimolecular film is illustrated in
As a material of the transparent electrodes 41 and 42, a material similar to that of the transparent electrode 12 is able to be used. Specifically, the transparent electrodes 41 and 42 are made of a conductive material transparent to light used for light excitation such as ITO, FTO, and NESA glass, an extremely thin Au film capable of transmitting light or the like.
Next, a description will be given of a manufacturing method of the non-wetted all solid protein transparent light-receiving device.
First, a solution containing the electron transfer proteins 43a, specifically, a protein solution obtained by dissolving the electron transfer proteins 43a in a buffer solution containing water is attached onto one of the transparent electrodes 41 and 42, for example, onto the transparent electrode 41 by liquid drop method, spin coat method, dip method, spray method or the like. Next, the resultant obtained by attaching the protein solution onto the transparent electrode 41 is retained at room temperature or at temperature lower than room temperature. Thereby, the electron transfer proteins 43a in the attached protein solution are immobilized onto the transparent electrode 41.
Next, the resultant obtained by immobilizing the electron transfer proteins 43a in the protein solution onto the transparent electrode 41 is heated up to temperature lower than denaturation temperature of the electron transfer protein 43a and dried. Thereby, the liquid contained in the protein solution is all evaporated and removed.
Accordingly, only the electron transfer proteins 43a are immobilized onto the transparent electrode 41, and thereby the solid protein layer 43 is formed. The thickness of the solid protein layer 43 is able to be easily controlled by the amount of the protein solution attached onto the transparent electrode 41, the concentration of the protein solution and the like. Next, the transparent electrode 42 is formed on the solid protein layer 43. The transparent electrode 42 is able to be formed by depositing a conductive material by sputtering method, vacuum evaporation method or the like.
Accordingly, the intended non-wetted all solid protein transparent light-receiving device is manufactured.
Next, a description will be given of operation of the non-wetted all solid protein transparent light-receiving device.
A voltage (a bias voltage) is applied between the transparent electrode 41 and the transparent electrode 42 of the non-wetted all solid protein transparent light-receiving device so that the transparent electrode 42 side has lower electric potential. In the case where light does not enter the solid protein layer 43 of the non-wetted all solid protein transparent light-receiving device, the solid protein layer 43 is insulative and a current is not flown between the transparent electrode 41 and the transparent electrode 42. Such a state is off-state of the non-wetted all solid protein transparent light-receiving device. Meanwhile, as illustrated in
As illustrated in
Protein solutions (200 μM) obtained by respectively dissolving the tin-substituted horse heart cytochrome c, the tin-substituted bovine heart cytochrome c, and the zinc-substituted horse heart cytochrome c in concentrated form in Tris-HCl buffer solution (pH8.0) were prepared.
Next, as illustrated in
Next, the resultant was left for 2 hours at room temperature, or for a day and a night at 4 deg C., and thereby the tin-substituted horse heart cytochrome c, the tin-substituted bovine heart cytochrome c, or the zinc-substituted horse heart cytochrome c in the protein droplet 53 was immobilized onto the ITO electrode 52.
Next, the samples were put into a drier machine retained at 30 to 40 deg C. both inclusive, and were dried for 30 to 60 minutes both inclusive. By such drying process, liquid such as water contained in the protein droplet 53 was vaporized and removed. In the result, only the tin-substituted horse heart cytochrome c, the tin-substituted bovine heart cytochrome c, or the zinc-substituted horse heart cytochrome c was left on the ITO electrode 52, and the solid protein layer 43 was formed as illustrated in
Next, as illustrated in
Accordingly, the non-wetted all solid protein transparent light-receiving device was manufactured. The cross sectional structure of the non-wetted all solid protein transparent light-receiving device is illustrated in
Many non-wetted all solid protein transparent light-receiving devices were manufactured as described above, and resistance between the transparent electrodes 54 and 55 was measured in the air. In the result, the resistance was distributed in a wide range from 1 kΩ to 30 MΩ both inclusive. The reason why the resistance between the transparent electrodes 54 and 55 was distributed in the wide range as described above was as follows. That is, the thickness of the solid protein layer 43 varied according to each device, or each type of the electron transfer proteins 43a composing the solid protein layer 43 varied according to each device.
Photocurrent action spectrum of the non-wetted all solid protein transparent light-receiving device was measured. As the electron transfer proteins 43a composing the solid protein layer 43, the tin-substituted horse heart cytochrome c and the zinc-substituted horse heart cytochrome c were used. Measurement was performed by connecting a working electrode of a potentiostat to the transparent electrode 54 connected to the ITO electrode 52, and connecting a counter electrode and a reference electrode to the transparent electrode 55. The transparent electrodes 54 and 55 were made of the Au film being 20 nm thick. Measurement result of action spectrum under potential of 0 mV and −800 mV in the case where the zinc-substituted horse heart cytochrome c was used as the electron transfer proteins 43a composing the solid protein layer 43 is illustrated in
The liquid type protein transparent light-receiving device was formed as described below. First, a given region on the surface of an ITO film formed on a glass substrate was masked with the use of a tape or a resin. Next, a portion of the ITO film not masked was removed by wet etching for 90 sec by using 12M HCl (50 deg C.). Next, after the glass substrate was washed with water, the mask was removed, and the resultant was dried in airflow. Next, the glass substrate was provided with ultrasonic treatment for 30 minutes in 1% Alconox (registered trademark) aqueous solution, was subsequently provided with ultrasonic treatment for 15 minutes in isopropanol, and was provided with ultrasonic treatment for 15 minutes in water twice. Next, after the glass substrate was soaked in 0.01 M NaOH for 3 minutes, the resultant was dried in airflow or nitrogen flow. After that, the glass substrate was provided with ultraviolet (UV)-ozone surface treatment for 15 minutes at about 60 deg C. Accordingly, the ITO electrode was formed. The ITO electrode was a working electrode. Next, in the first method, the ITO electrode formed as described above was rinsed with a protein solution (50 μM) obtained by dissolving the zinc-substituted horse cytochromes c in Tris-HC1 buffer solution (pH 8.0). Next, after the ITO electrode rinsed with the protein solution as above was retained for a night at 4 deg C., the resultant was rinsed with water and was dried in airflow or nitrogen flow. In the second method, the ITO electrode formed as described above was rinsed with a protein solution (50 μM) obtained by dissolving the zinc-substituted horse cytochromes c in Tris-HCl buffer solution (pH 8.0). Otherwise, the ITO electrode formed as described above was rinsed with a protein solution (5 μM) obtained by dissolving the zinc-substituted horse cytochromes c in sodium phosphate buffer solution (pH 7.0). Next, the ITO electrode rinsed with the protein solution as above was dried in vacuum. After that, the ITO electrode was rinsed with water and was dried in airflow or nitrogen flow. As described above, a protein immobilized electrode in which the protein was immobilized onto the ITO electrode was formed. Next, the protein side of the protein immobilized electrode was placed opposite a clean ITO electrode separately formed as a counter electrode with a given distance in between. Outer circumferential sections of the protein immobilized electrode and the ITO electrode were sealed with a resin. In the ITO electrode as the counter electrode, a pinhole that communicates with a space between the protein immobilized electrode and the ITO electrode was formed as an air hole. Next, the resultant obtained by sealing the circumferential sections of the protein immobilized electrode and the ITO electrode with the resin was soaked in an electrolyte solution contained in a container. As the electrolyte solution, a solution obtained by dissolving 0.25 mM potassium ferrocyanide in 10 mM sodium phosphate buffer solution (pH 7.0) was used. Next, the container was retained in vacuum, and air in the space between the protein immobilized electrode and the ITO electrode was discharged outside from the foregoing pinhole. Next, the container was returned back under atmosphere pressure, and the space between the protein immobilized electrode and the ITO electrode was filled with the electrolyte solution. After that, the foregoing pinhole was sealed with a resin. Accordingly, the liquid type protein transparent light-receiving device was formed.
The light degradation curves illustrated in
f(x)=a×exp(b×x)+c×exp(d×x)
Coefficients a, b, c, and d of the function f(x) are as follows. Numerical values in parentheses of each coefficient indicate 95% confidence interval.
Liquid type protein transparent light-receiving device
a=5.204×10−9(5.029×10−9, 5.378×10−9)
b=−0.00412(−0.00441, −0.003831)
c=1.799×10−11(2.062×10−11, 3.392×10−10)
d=−0.0004618(−0.000978, −2.58×10−5)
Non-wetted all solid protein transparent light-receiving device
a=5.067×10−11(4.883×10−11, 5.251×10−11)
b=−0.0009805(−0.001036, −0.0009249)
c=4.785×10−11(4.58×10−11, 4.99×10−11)
d=−0.0001298(−0.0001374, −0.0001222)
Life t of the non-wetted all solid protein transparent light-receiving device and the liquid type protein transparent light-receiving device is defined as t=[a/(a+c)](−1/b)+[c/(a+c)](−1/d). According to the definition, the life of the liquid type protein transparent light-receiving device is 306 sec, while the life of the non-wetted all solid protein transparent light-receiving device is 4266 sec. Thus, it is found that the life of the non-wetted all solid protein transparent light-receiving device is at least 14 times as much as the life of the liquid type protein transparent light-receiving device.
In addition, in the light degradation curve of the liquid type protein transparent light-receiving device illustrated in
Next, a description will be given of results of measuring frequency response of the non-wetted all solid protein transparent light-receiving device and the liquid type protein transparent light-receiving device.
The light degradation curves illustrated in
f(x)=a×exp(b×x)+c×exp(d×x)
Coefficients a, b, c, and d of the function f(x) are as follows. Liquid type protein transparent light-receiving device
a=1.72×10−8
b=−0.00462
c=3.51×10−9
d=−0.000668
Non-wetted all solid protein transparent light-receiving device (monomolecular film)
a=0.4515
b=−0.002599
c=0.3444
d=−0.0001963
Non-wetted all solid protein transparent light-receiving device (multimolecular film)
a=0.5992
b=−0.002991
c=0.2371
d=−0.0001513
In this case, light degradation average time constant of the non-wetted all solid protein transparent light-receiving device and the liquid type protein transparent light-receiving device was as follows.
Liquid type protein transparent light-receiving device: 2.54×102 sec Non-wetted all solid protein transparent light-receiving device (monomolecular film): 2.71×103 sec Non-wetted all solid protein transparent light-receiving device (multimolecular film): 2.73×103 sec
As described above, life t of the non-wetted all solid protein transparent light-receiving device and the liquid type protein transparent light-receiving device is defined as t=[a/(a+c)](−1/b)+[c/(a+c)](−1/d). According to the definition, the life of the liquid type protein transparent light-receiving device is 434 sec, while the life of the non-wetted all solid protein transparent light-receiving device (monomolecular film) is 2423 sec, and the life of the non-wetted all solid protein transparent light-receiving device (multimolecular film) is 2113 sec. Thus, it is found that the life of the non-wetted all solid protein transparent light-receiving device is at least about 5 times as much as the life of the liquid type protein transparent light-receiving device.
According to the multilayer transparent light-receiving device according to the fourth embodiment, the following various advantages are able to be obtained. That is, in the non-wetted all solid protein transparent light-receiving device used as the protein transparent light-receiving element 1 composing the multilayer transparent light-receiving device, water does not exist inside the device, and operation is enabled without being contacted with water. Thus, as a light-receiving device replacing the existing light-receiving device using semiconductor, the non-wetted all solid protein transparent light-receiving device is able to be mounted onto an electronic device. Further, in the non-wetted all solid protein transparent light-receiving device, since water does not exist inside the device, heat denaturation, radical damage, decay and the like of a protein the resulting from existence of water are able to be prevented, stability is high, and durability is superior. Further, in the non-wetted all solid protein transparent light-receiving device, since water does not exist inside and outside the device, there is no possibility of electric shock, and intensity is easily secured.
Moreover, in the non-wetted all solid protein transparent light-receiving device, the solid protein layer 43 is directly immobilized onto the transparent electrodes 41 and 42 without a linker molecule or the like in between. Thus, compared to a case that the non-wetted all solid protein transparent light-receiving device is immobilized onto the transparent electrodes 41 and 42 with the linker molecule or the like in between, a larger photocurrent is able to be obtained. Further, in addition to the fact that the solid protein layer 43 is directly immobilized onto the transparent electrodes 41 and 42, the solid protein layer 43 is able to be formed significantly thinly. Thus, the distance between the transparent electrode 41 and the transparent electrode 22 is able to be significantly shortened. Therefore, the non-wetted all solid protein transparent light-receiving device is able to be formed thinly. In addition, by transparentizing the transparent electrodes 41 and 42, a plurality of the non-wetted all solid protein transparent light-receiving devices are able to be laminated. Furthermore, in the non-wetted all solid protein transparent light-receiving device, the size of the electron transfer protein 43a composing the solid protein layer 43 is significantly small, about 2 nm. Thus, for example, it is possible to significantly precisely detect light incidence position in the solid protein layer 43. Thus, a high-definition optical sensor or a high-definition image pickup device is able to be achieved.
Further, it is suspected that photo conductive effect of the electron transfer protein 43a results from “one photon multielectron generation.” However, in the liquid protein transparent light-receiving device, since resistance of the solution (solution resistance) existing between the electrodes is high, the foregoing “one photon multielectron generation” is possibly prevented. Meanwhile, in the non-wetted all solid protein transparent light-receiving device, since the solution resistance does not exist, “one photon multielectron generation” is enabled, significant improvement of photoelectric conversion efficiency is able to be improved, and a higher photocurrent is able to be obtained.
The non-wetted all solid protein transparent light-receiving device is able to achieve an optical switching device, an optical sensor, an image pickup device and the like. As described above, since frequency response of the non-wetted all solid protein transparent light-receiving device is fast, the non-wetted all solid protein transparent light-receiving device is able to achieve an optical switching device capable of high-speed switching, a high-speed response optical sensor, an image pickup device capable of capturing an object moving at a high speed and the like. Further, in the case where the non-wetted all solid protein transparent light-receiving device is used for the optical switching device, the optical sensor, the image pickup device and the like, a superior electronic device is able to be achieved.
For example, as will be illustrated later, a camera capable of concurrently focusing on a plurality of objects located in a position different from each other by using one lens is able to be achieved. Further, by using the multilayer transparent light-receiving device, multifocusing and high-speed focusing are enabled with the use of a single lens. Further, in the case where the multilayer transparent light-receiving device is used as a light-receiving device of an optical disc system using a multilayer optical disc or an optical recording reproduction system using a holographic recording medium, parallel readout of the multilayer optical disc and readout of the holographic recording medium are able to be easily performed at a high speed.
A multilayer transparent light-receiving device according to a fifth embodiment has a structure that N layers of the protein transparent light-receiving element 1 are laminated as the multilayer transparent light-receiving device according to the first embodiment. The multilayer transparent light-receiving device according to the fifth embodiment is different from the first embodiment in that multiple pixels composed of the protein transparent light-receiving element 1 are in-plane integrated.
That is, as illustrated in
For extracting and processing a signal from the respective pixels 62 in the integrated multilayer transparent light-receiving device and the like, existing known techniques are able to be used. For example, wiring is formed in the line direction and in the column direction to be connected with electrodes above and below the respective pixels 62 arranged in a state of two dimensional matrix in m lines and n columns. In addition, for example, for reading a signal from the m pieces of the pixel 62 in a selected column, a given bias voltage is applied only to wiring connected to one electrode of the pixels 62 in the column, and a photocurrent flown in wiring connected to the other electrode of the pixels 62 in m line is detected.
According to the fifth embodiment, advantages similar to those of the first embodiment are able to be obtained. Further, the integrated multilayer transparent light-receiving device is available for applications similar to those of the multilayer transparent light-receiving device according to the first embodiment.
As illustrated in
For extracting and processing a signal from the respective pixels 62 in the integrated multilayer transparent light-receiving device and the like, existing known techniques are able to be used.
According to the sixth embodiment, advantages similar to those of the first embodiment are able to be obtained.
Further, the integrated multilayer transparent light-receiving device is available for applications similar to those of the multilayer transparent light-receiving device according to the first embodiment.
In a stereoscopic imaging system according to a seventh embodiment, a camera including the integrated multilayer transparent light-receiving device according to the fifth embodiment or the sixth embodiment is used as an optical sensor. The camera is a digital camera, a video camera or the like.
The camera is configured so that the optical axis direction of an image pickup optical system of the camera corresponds with the lamination direction of the pixel 62 composed of the protein transparent light-receiving element 1 of the integrated multilayer transparent light-receiving device. Thereby, in this camera, the respective N stages of light receiving face of the integrated multilayer transparent light-receiving device are able to be used for focusing in capturing an object. Therefore, all objects with each different distance from the camera are able to be focused on and captured. For example, in the case where a flower 72 is located with distance d1 from a camera 71 and a mountain 73 is located with distance d2 (d2>d1) from the camera 71 as illustrated in
A description will be given of a case that an image captured by the camera 71 is displayed on a display.
In the first example, a realistic three dimensional image captured by the camera 71 is displayed on the display. For example, a realistic three dimensional image in which the flower 71 looks forward and the mountain 72 looks rearward is able to be displayed.
In the second example, a section particularly desired to be viewed in a three dimensional image captured by the camera 71 is displayed emphatically on the display. For example, in the example of
A description will be given of the fact that the respective N stages of light receiving face (faces of the electron transfer protein layer 13) of the integrated multilayer transparent light-receiving device are able to be used for focusing in capturing an object in detail again.
A description will be given of change of position of an imaging face in the integrated multilayer transparent light-receiving device according to distance of an object from the lens L, in other words, change of focus location. As illustrated in
As evidenced by Table 5 and
In the case where the imaging face of the object image by the lens L does not correspond with the light receiving face of the integrated multilayer transparent light-receiving device, in other words, in the case where it is not focused on the light receiving face, an object image is able to be restructured by algorithm of software based on a signal obtained on the respective light receiving faces.
Now, as illustrated in
For example, by using the foregoing technique in capturing by a television camera in a broadcast station, in the case where an image is displayed on a three dimensional television by using a video signal transmitted from the broadcast station, a portion particularly desired to be viewed by a user in the displayed images is able to be freely zoomed in or zoomed out based on an output signal from the light receiving face of the integrated multilayer transparent light-receiving device.
By using the camera 71, a clear image of a plurality of things (objects) with each distance different from each other from the camera 71 is able to be concurrently obtained. For example, as illustrated in
By using the camera 71, an object desired to be captured is able to be focused on at high velocities. For example, a case that a soccer game is held in a soccer coat 79 and the game is captured by the camera 71 as illustrated in
That is, as illustrated in
By using the camera 71, chromatic aberration is able to be corrected without using an expensive achromatic lens. That is, as illustrated in
In a stereoscopic imaging system according to an eighth embodiment, a camera including the integrated multilayer transparent light-receiving device according to the sixth embodiment is used as an optical sensor.
As illustrated in
In a stereoscopic imaging system according to a ninth embodiment, a camera including the integrated multilayer transparent light-receiving device according to the sixth embodiment is used as a light-receiving device.
As illustrated in
As illustrated in
The present invention has been specifically described with reference to the embodiments and the example of the present invention. However, the present invention is not limited to the foregoing embodiments and the foregoing example, and various modifications may be made based on the technical idea of the present invention. For example, the numerical values, the structures, the configurations, the shapes, the materials and the like described in the foregoing embodiments and the foregoing example are only examples. Numerical values, structures, configurations, shapes, materials and the like different from those described in the foregoing embodiments and the foregoing example are able to be used according to needs.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-252778 | Nov 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/069197 | 10/29/2010 | WO | 00 | 11/14/2011 |
