The present invention relates to a micromechanical photothermal analyser of microfluidic samples, comprising an oblong micro-channel extending longitudinally from a support element, the micro-channel is made from at least two materials with different thermal expansion coefficients, wherein the materials are arranged relatively to each other so that heating of the micro-channel results in a bending of the micro-channel, the first material has a first thermal expansion coefficient and is made from a light-specific transparent penetrable material so that when exposed to ultraviolet (UV), visible (VIS), or infrared (IR) light, the specific-light radiates into the channel through said light transparent material, the second material has a second thermal expansion coefficient being different from the first thermal expansion coefficient. The micromechanical photothermal analyser also comprises an irradiation source being adapted to radiate UV, VIS, or IR light towards and through the transparent micro-channel, and a deflection detector being adapted to detect the amount of deflection of the micro-channel.
The analysis of small volumes of liquid by light absorption techniques, such as infrared spectroscopy or UV-VIS absorption spectroscopy, remains as a formidable challenge.
Fino E et al discloses in the article “Visible photothermal deflection spectroscopy using microcantilevers” (Sensor and Actuators B 169 (2012) 222-228, Elsevier) a flat cantilever with a rectangular cross section. This cantilever lacks a capability to analyze liquids and/or gases. The cantilever disclosed is composed from a bare silicon microcantilever coated with gold.
US 2005/064581 disclose an apparatus for detecting an analyte that has a suspended beam containing at least one microfluidic channel containing a capture ligand that bonds to or reacts with an analyte. The method disclosed, aims at determining an amount bound by measuring the change in resonant frequency during the adsorption.
However, none of method disclosed have been found suitable for analyzing liquid or gaseous substance by use of absorption spectroscopy.
Hence, an improved device and method for absorption spectroscopy of liquid and gas samples, preferably in the nano or pico-liter volume range would be advantageous, and in particular a more efficient and/or reliable analytical device and method would be advantageous.
It is a further object of the present invention to provide an alternative to the prior art.
In particular, it may be seen as an object of the present invention to provide a micron-scale analyser that solves the above mentioned problems of the prior art.
Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a micromechanical photothermal analyser of microfluidic samples comprising:
The irradiation source is preferably adapted of controlled radiation, e.g. where the wavelength and/or pulsation is controlled in a predefined manner.
As it appears from the description of the invention herein, the micromechanical, and in particular the micro-channel, may be orientated in space, during use, with its longitudinal direct being horizontal (as shown in the figures). Thus, the oblong micro-channel may be characterised as a bi-material cantilever, where the cantilever comprising two longitudinal extending layers with different thermal expansion coefficient. As presented herein, the interior of the micro-channel (also extending longitudinal) may preferably be formed inside one of such layers.
The bending of the micro-channel by heating is typically provided by the micro-channel comprising a first wall segment and a second wall segment (having different thermal expansion coefficient), where the first wall segment extends longitudinally along the second wall segment.
In preferred embodiment, the first material is transparent such as semitransparent to one or more of: visible light, ultraviolet and infrared light.
In preferred embodiments, the thermal expansion coefficient of the first material (first thermal expansion coefficient) is larger than the thermal expansion coefficient of the second material (second thermal expansion coefficient).
In other preferred embodiments, the thermal expansion coefficient of the first material (first thermal expansion coefficient) is smaller than the thermal expansion coefficient of the second material (second thermal expansion coefficient).
Thermal expansion coefficient as used herein, is used in a manner being ordinary to the skilled person.
A micromechanical photothermal analyser of microfluidic samples according to the present invention may be used to analyse a fluid, such as a gas or a liquid, to reveal one or more characteristics of the fluid thereby characterising the fluid. Accordingly, the term analyser is to be understood in broad terms to include the meaning detector, analyser, sensor, etc.
An important feature of the present invention may be seen to be a photothermal detector, in the form of the oblong micro-channel which is based on or constituted by a bimaterial micro-channel, for the analysis of microfluidic samples. This detector can e.g. be used to record a photothermal IR spectrum of a substance inside a micro-channel when scanning the wavelength of the probing light.
However, the light may be other types of lights and it is envisaged that the invention is not limited to use within the IR range. E.g. concentrations of organic molecules in water may typically be measured with UV absorption measurements, and e.g. highly efficient fluorescence methods are working in the visible range.
In a particular aspect, an IR spectroscopic technique based on calorimetry for characterization of picoliter volume of liquids contained in a micro-channel that is temperature sensitive is demonstrated. IR absorption by liquid analyte in the channel creates minute heat that causes the oblong micro-channel to bend as a function of illuminating IR producing a nonmechanical IR absorption spectrum. This technique overcomes the sample volume limitation of current IR microspectroscopy and can be integrated into microfluidic devices allowing for an online sample analysis. In addition, the micro-channel geometry allows the precise measurements of the density of the liquid sample by monitoring the resonance frequency of the micro-channel. Significant and intriguing applications, such as drug development and screening, direct monitoring of byproducts from a micro bio-reactor, or the study of cells and microbes, are anticipated by the integration of more sophisticated microfluidics with this calorimetric IR microspectroscopy.
As there exist a correlation between the deflection of the micro-channel and the absorbed/heat generated in the micromechanical photothermal analyser according to the present invention, such analysers may be applied for numerous purposes.
An analyser according to the invention may successfully identify different substances (using their small amounts) based on the light-wavelength dependent deflection (as these may be seen as a unique finger print for each substance). An analyser according to the invention may also be used to monitor activities of bio cells due to their production of heat during growth. Additionally chemical reaction by mixing minute amounts (picoliters) of two different chemicals (compatible to the material of the device) can also be monitored by an analyser according to the present invention. An analyser according to the invention may further be used to monitor the concentration of chemical compounds in the microfluidic sample by UV-VIS absorption measurements.
In the present context, terms are used in a manner being ordinary to a skilled person. However, some the used terms are explained in some details below:
Light-specific transparent penetrable material is preferably used to denote a material being transparent to a specific and selected window of wavelengths.
Micron-scale or micro-sized is preferably used to denote element(s) having a size in the micron meter range scale i.e. having dimension in the range of 10−6 m.
Micro-channel is preferably used to denote a channel having a longitudinal extension in the micro meter to milli meter range as well as having a cross section in the nano meter to micro meter range. Further, micro-channel is preferably used to denote a microfluidic channel having a closed cross section. A micro-channel is tubular shaped in the sense that it is not open to exterior of the micro-channel except at inlet(s)/outlet(s).
Microfluidic is preferably used to denote a volume in the femto litre to micro litre range
Nano-scale or nano-sized is preferably used to denote element(s) having a size in the nano meter range scale, i.e. having dimensions in the range of 10−9 m.
Micromechanical photothermal analyser is preferably used to mean a device adapted to perform photothermal analysis as disclosed herein and being based on an oblong micro-channel being micron or nano sized.
Oblong micro-channel is preferably used to mean a fluid channel in the form of an elongate member anchored at only one end at a support element. An oblong micro-channel may also be described as and single clamped structure. Oblong micro-channel and micro-channel is preferably used interchangeably herein.
Oblong is used to denote an element having a length being larger than both the width and height of the element.
Orientations given herein are preferably given with respect to the orientation of the elements presented in the figures. While the figures presents preferred orientation of the elements with gravity pointing downwards, it is noted that the elements may be orientated differently during use.
The present invention relates in a second aspect to a photothermal analysis method using a micromechanical photothermal analyser according to the first aspect of the invention. The method preferably comprising
The first and second aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Further, a micromechanical analyser has also the ability to analyse a sample it its solid state.
An advantageous feature of the present invention is that throughout the measurement—or analysing in general—the oblong micro-channel as well as analyte may be kept at atmospheric pressure and room temperature, while still allowing for other arranging the oblong micro-channel in other conditions.
Further embodiments are presented below and in the accompanying claims.
The present invention and in particular preferred embodiments thereof will now be disclosed in connection with the accompanying drawings. The drawings show ways of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.
Reference is made to
The sample analysis is carried out based on deflection of a micro-channel due to thermal bending of the channel. With reference to
The micro-channel is made from at least two materials with different thermal expansion coefficients, wherein the materials are arranged relatively to each other so that heating of the micro-channel 1 results in a bending of the micro-channel 1. The first material has a first thermal expansion coefficient and is made from a light-specific transparent penetrable material so that when exposed to UV, VIS, or IR light, the specific light radiates into the channel 2 through said light-specific transparent material. The second material has a second thermal expansion coefficient being different from the first thermal expansion coefficient.
As shown in
The first wall segment 4 defines the interior 2 of the micro-channel 1 and the second wall segment 11 is arranged, such as constitute a coating, on a lower surface of the first wall segment 4, or, in general, arranged such as constitute a coating on a longitudinal extending surface of the first wall segment 4.
It can be realised from figures and the description accompanying these figures that for instance the wording “the first wall segment 4 extends longitudinally above the second wall segment 11” has the general meaning that the first wall segment 4 extends longitudinally along the second wall segment 11 (or vice versa). That also typically means that the two wall segments forms longitudinal extending elements (layers) of a cantilever. Similarly, “upper respectively lower wall”, e.g., refers to that the two walls are arranged as longitudinal extending elements of a cantilever. The orientation referred to herein may alternatively be in relation to the position of the irradiation source and the micro-channel relatively to each other. In such situations, the wall segment facing towards the irradiation source is typically the upper wall segment.
The liquid—or fluid in general—to be analysed is contained in the interior 2 of micro-channel 1 extending inside the oblong micro-channel 1 in the longitudinal direction of the oblong micro-channel 1.
The difference in thermal expansion coefficients of the two materials and their relative orientations results in a bending of the oblong micro-channel 1 if the temperature of the oblong micro-channel 1 deviates from a so-called equilibrium temperature, being the temperature at which the oblong micro-channel 1 is straight. This bending is used in the present invention to characterise a fluid arranged inside the channel 1 by heating the oblong micro-channel indirectly by heating the fluid by infrared radiation.
To accomplish the heating, the micromechanical photothermal analyser further comprising an irradiation source 3 being adapted to ray UV, VIS, or IR light 6 towards and through the first wall segment 4. Thereby, the fluid is heated which will cause a heating of the micro-channel 1 resulting in a bending thereof.
The irradiation source 3 is adapted to irradiate pulses or continuous beam of light. Furthermore, the irradiation source 3 is adapted to irradiate light at difference wavelengths. For the proof of concept, the IR source was able to emit IR from 6 μm to 12 μm in wavelength. Depending upon a material, only a selective range of IR wavelengths was used.
The amount of deflection is determined by a deflection detector 8 being adapted to detect the amount of deflection of the micro-channel 1. The deflection detector 8 comprising a laser emitting light towards the micro-channel in an oblique direction and a position sensitive detector arranged to receive the laser light reflected from the micro-channel (see also
Fluid, such as liquid, is fed into and led out from the interior 2 of the micro-channel 1 by an inlet and an outlet. In many preferred embodiments, the fluid does not flow through the micro-channel 1 during analysing and the fluid is initially fed into the channel 2, heated and subsequently emptied out from the channel. However, the actual use of the micromechanical photothermal analyser is often dictated by the amount of sample available and it is envisaged that the micromechanical photothermal analyser may be used in way where the fluid flow through the micro-channel 1 during analysing.
As seen from
With reference to
A preferred selection of the material form which the micro-channel 1 is made is Silicon Nitride for the first wall segment 4 and metal or material coated with metal for the second wall segment 11. However, the selection of the material may differ from Silicon Nitride and/or metal coating. It is noted, that the absorption spectrum is measured of the material present in the interior of the micro-channel 2 and that the material of the micro-channel may not influence the absorption spectrum at all wavelengths.
Reference is made to
As shown in
As the irradiation source 3 irradiates light into the fluid contained in the micro-channel 1, heating occurs at a specific wave length of the light (specific for a specific substance) which results in a bending of the micro-channel 1 as shown in
Reference is made to
Reference is made to
In a further embodiment (not shown in the figures) the first wall segment 4 is concave shaped and the second wall segment 11 is plate shaped. Thus, the first wall 4 segment may be viewed as constituting an open channel like a groove. The channel is closed by the first wall segment 4 being sealingly joined (to provide a fluid tight seal) with the second wall segment (11) whereby the concavity of the first wall segment is closed by the second wall segment (11) thereby defining the channel (2).
Reference is made to
As in the embodiment of
Again, the micro-channel is made from at least two materials with different thermal expansion coefficients, wherein the materials are arranged relatively to each other so that heating of the micro-channel 1 results in a bending of the micro-channel 1. The first material has a first thermal expansion coefficient and is made from a light-specific transparent penetrable material so that when exposed to UV, VIS, or IR light, the specific light radiates into the channel 2 through said light-specific transparent material. The second material has a second thermal expansion coefficient being different from the first thermal expansion coefficient.
As shown in
The first wall segment 4 defines the interior 2 of the micro-channel 1 and the second wall segment 11 is arranged, such as constitute a coating, on a lower surface of the first wall segment 4, or, in general, is arranged such as constituting a coating on a longitudinal extending surface of the first wall segment 4.
The liquid—or fluid in general—to be analysed is contained in the interior 2 of micro-channel 1 extending inside the oblong micro-channel 1 in the longitudinal direction of the oblong micro-channel 1.
The working principle due to the difference in thermal expansion coefficients is as disclosed in connection with inter alia
As shown in
The pillars 12 are typically equal to each other and are shaped as rods having a cylindrical outer shape. The height of the pillars equal the height of the interior of the channel and the diameter (or an equivalent diameter D=sqrt (4/π*cross sectional area) is typically selected smaller than ½ the width, such as smaller the ⅓ the width, and even smaller than ¼ the width of a channel branch. As indicated by the wording “micro-pillars” the dimensions of such elements are typically in the micro-meter range; however, the may also be in the nano-meter range.
As disclosed inter alia with reference to
The emission of light is typically carried out at a plurality of different wave lengths.
The determination of the fluid is based on a database look-up, the database is storing experimentally obtained correlations between deflections and substances. Usually, such a database may advantageously be developed by use of conventional IR spectroscopy.
In the following, further details and aspects of the invention will be presented.
Conventional IR microspectroscopy, which relies on Beer-Lambert's law, is based on detecting small intensity changes in the transmitted light through the sample using a cooled IR detector in a large inherent IR background. Increasing the incident IR power increases the background signal without enhancing the signal-to-noise ratio (SNR). In contrast, in calorimetric IR spectroscopy the IR absorption induces changes in the sample temperature, which results in an enhanced SNR with increasing incident IR power. IR absorption-induced temperature changes can be measured if the sample is deposited on a bi-material oblong micro-channel, which undergoes bending in proportion to the changes in its temperature. IR spectra of solid phase materials with mass in the range of tens of picogram placed on a bi-material oblong micro-channel have been measured using this calorimetric approach where the sample is illuminated with IR light from a quantum cascade laser. The mechanical bending of the oblong micro-channel as a function of illuminating wavelength resembles the conventional IR absorption spectra of the sample. However, IR characterization of similar amounts of liquids using this calorimetric method remained as challenge until now. IR characterization of very small amount of liquids has a plethora of potential applications, for example drug screening in pharmaceutical industry and characterization of samples in biomedical applications.
Reference is made to
The present invention offers an elegant technique for obtaining the IR absorption spectrum as well as density of the confined fluid in real time. In this invention, picoliter volume of fluid sample contained in the microfluidic channel on top of a bi-material oblong micro-channel absorbs IR photons at a certain wavelength and releases the energy to the phonon background of the bi-material micro-channel through multiple steps of vibrational energy relaxation. These nonradiative decay processes result in minute change in the temperature of the bi-material oblong micro-channel because of its low thermal mass, generating a measurable deflection of the oblong micro-channel (
Reference is made to
Introduction to the Oblong Micro-Channel Chip
The oblong micro-channel is fabricated with silicon rich silicon nitride (SRN) thus producing a transparent micro-channel (refractive index 2.02) in the visible spectrum. On four inch wafers, 10 mm×5 mm oblong micro-channel chips are fabricated at Danchip (nanofabrication facility in Denmark) at the Technical University of Denmark. On a 350 μm thick substrate, 500 nm thick SRN film is deposited. This lays down the bottom of the oblong micro-channel. This is followed by 3 μm thick layer of poly silicon as a sacrificial material. The patterned sacrificial layer is covered by another SRN thus making walls and top of the oblong micro-channel. All thin film deposition is performed by low pressure chemical vapor deposition (LPCVD) technique. Later, the sacrificial material is etched by wet etching using potassium hydroxide (KOH) at 80° C. Depending upon the length of an oblong micro-channel, the wet etching may take up to 18 hours in completely removing the sacrificial material thus forming micro-channels. Etching of SRN is almost negligible in KOH. Additionally the low stress nature of silicon nitride helps significantly in keeping the microchannel free of cracks. 350 μm thick substrate is particularly used to keep inlet (on back side of the chip) to be 550 μm wide which creates an opening of 100 μm on top side by KOH etching while following the anisotropic Si etch along 111 plane.
U-shaped microfluidic channel with dimensions of 16 μm in width, 1000 μm in length, and 3 μm in height is fabricated on top of a plain oblong micro-channel with dimensions of 44 μm in width, 500 μm in length, and 500 nm in thickness. This oblong micro-channel structure is rendered into a bi-material beam by depositing a 500 nm thick layer of aluminum on its bottom side using e-beam evaporation. This bi-material oblong micro-channel is supported on a 350 μm thick silicon chip, which provides two fluidic inlet and outlet (3×150 μm2, height×width) for delivering samples into the micro-channel on the oblong micro-channel (
The chip containing an oblong micro-channel and sample delivering channels is packaged in a holder made of polyether ether ketone (PEEK) that provides a connection with larger tubes to deliver a fluid sample to the oblong micro-channel.
The sealed contact between PEEK holder and the chip is achieved by placing a polydimethylsiloxane (PDMS) gasket and pressing the top of the chip by an O-ring made of nitrile butadiene rubber (NBR) (
Measurement Setup
An external-cavity Quantum Cascade Lasers (QCLs) (from Daylight Solutions) are used as a source of infrared (IR) light. General advantages of QCLs over a thermal IR source are; pulsed operation (up to 200 kHz), high optical power (up to 500 mW peak power), operation at room temperature, broad tunability, high spectral resolution (down to 0.1 nm) and compact assembly. For our experiments, the three QCL lasers are used (MIRCat™ (bandwidth: 6 μm to 13 μm), UT-7 (bandwidth: 6.4 μm to 7.4 μm, i.e. 1540 cm−1 to 1345 cm−1) and UT-8 (bandwidth: 7.1 μm to 8.7 μm, i.e. 1408 cm−1 to 1145 cm−1)).
The UT-8 QCL is pulsed at 200 kHz while UT-7 and MIRCat™ are pulsed at 100 kHz. The 100 or 200 kHz pulsed IR light with 5 or 10% duty cycle from three different quantum cascade lasers (QCL) is electrically burst at 80 Hz, directed to the oblong micro-channel, and scanned sequentially with a spectral resolution of 2 nm. This means that the cantilever is exposed to IR pulse every 12.5 milliseconds or 6.25 milliseconds. This time period is enough to provide thermal relaxation to the oblong micro-channel. To find amplitude of a signal at 80 Hz, the signal from the y-axis of the PSD is fed into a lock in amplifier (SR-850 from Stanford Research Systems). To continuously measure resonance frequency of the oblong micro-channel, a spectrum analyzer is used to measure fast Fourier transform (FFT) of the signal from the y-axis of the PSD. An oscilloscope is used to monitor and keep the laser spot in the center of the sensitive area of PSD. The data from the lock-in-amplifier and the spectrum analyzer are stored in a computer using a data acquisition card and a Labview program. Later the signal is plotted with respect to wavelength of IR light thus generating an IR spectrum of an analyte inside the oblong micro-channel. (
The photothermal oblong micro-channel deflection signal and the resonance frequency of the oblong micro-channel are simultaneously measured by optical beam deflection method where a probing red laser (with a spot size of about 50 μm) is reflected to a four quadrant position sensitive detector (PSD) (
Loading Liquid samples
To load a sample inside the oblong micro-channel, a vacuum pump is connected at the outlet tube which creates a pressure difference of 1000 mbar. This pulls a liquid sample inside the oblong micro-channel. Due to hydrophilic nature of SRN, a liquid sample instantly fills the micro-channel. The presence of a sample inside the oblong micro-channel is verified visually (through the transparent SRN channel) and change in its resonance frequency. For a new sample, generally a sample of up to 2 μL is loaded while for established experiments a sample as low as 500 pL is enough. The IR spectrum is collected with the 50 pL of a liquid sample which is inside of the oblong micro-channel located on top of the oblong micro-channel. The well-sealed packaging makes it convenient to measure IR spectrum of volatile liquid samples. Once an IR spectrum is measured, the sample is unloaded by applying a negative pressure at outlet of the chip. The chip is flushed with ethanol and water to remove residues of the sample.
Loading Solid/Viscous Samples
The oblong micro-channel is not only for liquid samples but it also has a capability to measure IR spectrum of samples which exist in solid or very viscous state. To take a measurement, the oblong micro-channel should be completely filled with a sample. In our experiments, a small quantity of such samples is placed on the backside of the oblong micro-channel ship, as shown in
IR Spectrum of an Empty Oblong Micro-Channel
In our experiments, as an analyte (in liquid or solid state) is placed in an oblong micro-channel and the oblong micro-channel is irradiated with IR light, the analyte as well as material (SRN) of the oblong micro-channel both absorb the photons at the respective resonance frequencies of their molecules. To get a distinct spectrum of an analyte, it is important to subtract the IR spectrum of SRN. For this purpose IR spectra (using all QCL modules) of an empty oblong micro-channel are measured as a baseline or background (as called in conventional IR spectroscopy) at a room temperature and atmospheric pressure. All subsequent measurements are performed at same ambient conditions.
Reference is made to
To demonstrate the capability of the calorimetric IR microspectroscopy with an oblong micro-channel, nanomechanical IR spectra of ampicillin sodium salt (C16H18N3NaO4S), antimicrobial drug agent, dissolved in de-ionized water with a concentration of 1, 2.5, 5, and 10% (w/w) are taken and compared with the conventional Fourier transform infrared (FTIR) spectra in attenuated total reflection (ATR) mode (
Reference is made to
To illustrate the capability of quantitative measurement and analysis, a oblong micro-channel is used to measure IR spectra of water-ethanol binary solutions with different concentrations of ethanol. Starting with 5% ethanol in a solution, the oblong micro-channel is irradiated with IR light from 1180 cm−1 to 1000 cm−1. All ethanol/water binary solutions exhibit strong peaks at 1087 cm−land 1053 cm−1 revealing C—O—H bending and C—O stretching respectively (
IR Spectrum of Multiple Analytes
Using the oblong micro-channel, we measured IR spectra of multiple organic analytes which includes n-hexadecane, isopropanol, naphtha, and paraffin. As all chemicals have common CH3 molecules so strong peaks are measured at 1380 cm−1 and 1460 cm−1 exhibiting symmetric and asymmetric CH3 deformation respectively. In addition to that isopropanol shows C—OH bending at 1250 cm−1 and CC—H in plane bending at 1345 cm−1. Paraffin and isopropanol exhibits CH2 twisting at 1308 cm−1 while at 1470 cm−1 paraffin exhibits CH2 bending. After smoothing by Savitzky-Golay filter the data is plotted in
This capability the oblong micro-channel of chemical characterization of liquids (by measuring IR spectra) is complemented with the quantitative measurement of physical properties of the liquids. The fundamental resonance frequency of an oblong micro-channel, f0, can be modeled as that of a solid oblong micro-channel with a changing density, given by
where λ0 is a constant related to the fundamental mode of the oblong micro-channel vibration (λ0=1.875), h, L, E are the effective thickness, the effective length, and the effective Young's modulus of the oblong micro-channel, respectively, Vc is a volume fraction of the oblong micro-channel, ρc is the effective mass density of the oblong micro-channel, Vf is a volume fraction of the fluid in the micro-channel and ρf is the mass density of the fluid in the micro-channel. With the assumption that the fluid in the micro-channel does not change the effective Young's modulus of the oblong micro-channel, Eq. 1 can be simplified to:
where A and B are constants which can be determined from the resonance frequency measurements of two different fluids with well-known mass densities, such as ethanol and de-ionized water. With determined A and B of the oblong micro-channel, the mass density of the fluid in the micro-channel can be determined by
Fundamental resonance frequencies of the oblong micro-channel are measured with three ethanol/water binary mixtures having 5, 10, and 20 mass percent of ethanol. The density is calculated from Eq. 2 (
Irrespective to a light source (ultraviolet, visible or IR), the oblong micro-channel can be effectively used as a miniature micromechanical photothermal analyser to show absorption of picoliter volume of a solution at specific wavelengths of light.
For a proof of concept, it is only demonstrated to measure nanomechanical spectra of ampicillin sodium salt and ethanol solutions. In future, we would like to identify cancer cells, pharmaceutical formulations and more complex chemicals through their interaction with light. Due to mass production and miniature size, the oblong micro-channel chips would be used in an array configuration to assess multiple analytes at a time. In our experiments, due to limited spectrum range of QCL sources, the oblong micro-channel could not be used over a large bandwidth but as the technology advances with external cavity lasers, we hope to get a QCL with a broader wavelength range.
Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms “comprising” or “comprises” do not exclude other possible elements or steps. Also, the mentioning of references such as “a” or “an” etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.
Number | Date | Country | Kind |
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13173787.6 | Jun 2013 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/DK2014/050192 | 6/26/2014 | WO | 00 |