Patent Application
20110236877
The present invention relates to a biosensor, particularly to a biosensor which uses surface acoustic wave (SAW) to test a liquid specimen. The present invention also relates to a method using the abovementioned biosensor to perform a bio-test, particularly to a method which analyzes the SAW variation caused by the weight decrease of the test polymer.
General biological samples or specimens are mainly tested with two methods. In one of the methods, extraction, concentration and deposition processes or mass spectrographic analysis and chromatography are used to separate and purify a biological sample or specimen, and then the sample or specimen is tested. In the other method, a specific reaction is used to directly assay an analyte in a complicated sample. For example, a biochip or sensor is used to assay whether an analyte exists.
A biosensor generally comprises an identification material, a transducer and a signal processor. When the identification material reacts with the analyte the transducer transforms the resultant physical or chemical variation into an electric signal. The signal processor analyzes the electric signal and obtains a test result. In order to get an accurate test result, the identification material must have specificity corresponding to the analyte. The common-seen identification materials include biological tissues, microbes, organelles, cell receptors, enzymes, antigens and antibodies.
Refer to
A R.O.C. publication No. 200804807 discloses a “Sensor for Detecting a Chemical or Biological Material”, wherein a biological label molecule is mixed with a sol-gel derivative to detect an analyte in a gas. An U.S. Pat. No. 5,658,732 discloses an “Assay Method for Biological Target Complexes on the Surface of a Biosensor”. An U.S. Pat. No. 5,814,525 discloses a “Piezoelectric Biosensor with a Ladder Polymer Substrate Coating”. These prior arts respectively disclose a piezoelectric biosensor and the method using the same to detect a biological specimen. They use a specific identification material to capture an analyte. The identification material has active binding sites to bond or couple with the analyte, whereby the analyte is detected.
Distinct from the abovementioned prior arts, the present invention proposes a biosensor which integrates a SAW device and a test polymer, and which detects the analyte according to the fact that the weight of the test polymer is substantially decreased by the reaction between the test polymer and the analyte.
One objective of the present invention is to provide a biosensor and a method using the same to perform a bio-test, whereby an analyte in a liquid specimen can be fast and sensitively detected.
To achieve the abovementioned objective, the present invention proposes a biosensor which integrates a SAW (Surface Acoustic Wave) device and a test polymer comprises a piezoelectric substrate, a first transducer, a second transducer and a test polymer. The test polymer is formed on the piezoelectric substrate and able to react with an analyte. The first and second transducers are formed on the piezoelectric substrate and respectively arranged at two sides of the test polymer. The first and second transducers are respectively defined to an output end and an input end of the surface acoustic wave. The present invention also proposes a method using the abovementioned biosensor to perform a biotest, wherein the test polymer reacts with the analyte and loses weight, such that the characteristics of the SAW are changed by the weight decrease of the test polymer. The biosensor detects and analyzes the variation of the SAW characteristics to determine the attributes and content of the analyte. The embodiments are described in detail in cooperation with the drawings to demonstrate the technical contents of the present invention.
The embodiments of the present invention are described in cooperation with the following drawings.
Below, the biosensor and the method using the same to perform a biotest are described simultaneously in accompany with the drawings to make easily understood the technical contents of the present invention. Refer to
In the abovementioned embodiment, the SAW device 20 is a shear horizontal SAW (SH-SAW for short) device. The piezoelectric substrate 201 is made of quartz, or lithium tantalate (LiTaO3).
Refer to
It should be further explained that the substantial weight decrease of the test polymer 21 means the decrease of the physical dimensions, such as the decrease of the volume, area or thickness of the test polymer 21, which results from the reaction between the test polymer 21 and the analyte 4 and results in the decrease of mass or density of the test polymer 21. Thus are varied the physical characteristics of the SAW passing through the test polymer 21. The test polymer 21 has specificity to the analyte 4. “Specificity” means that the test polymer 21 cannot react with any material in the liquid specimen 3 except the analyte 4. In another embodiment, water, normal saline or buffer solution that does not react with the test polymer 21 is used to flush the test polymer 21 to remove the liquid specimen 3; then the residual humidity is dried with a baking or air-blowing way without damaging the test polymer 21. In yet another embodiment, the test polymer 21 is a solid-state material.
The biosensor and the method using the same to perform a biotest of the present invention can fast detect the attributes and content of the analyte 4 and thus can aid disease diagnosis and contribute to biomedicine researches. In the conventional technology, a captured molecule or material is formed on a film to capture a specific analyte. For example, an antigen is used to capture an antibody. The present invention is distinct from the conventional technology in that the test polymer 21 reacts with the analyte 4 in the liquid specimen 3, and the analyte 4 is detected via detecting the variation of the SAW resulting from the decrease of the physical quantities of the test polymer 21.
In one embodiment, the present invention is applied to detect an enzyme. In this embodiment, the test polymer 21 is a gelatin or a hydrogel, which can react with the enzyme and is coated on the piezoelectric substrate 201. The gelatin or hydrogel is a solid-state material at or below the normal atmospheric temperature. When the polymer (such as gelatin, hydrogel and the like) reacts with the enzyme (such as a proteolytic enzyme or a gelatin enzyme), hydrolysis occurs. Then, a portion of the gelatin or hydrogel is decomposed into amino acids and liquefied into a liquid. The liquid product of hydrolysis is removed (washed or flushed away) together with the liquid specimen 3. Therefore, the specificity of the gelatin or hydrogel can be used to detect an enzyme-contained liquid specimen 3 in the present invention.
In one embodiment, the present invention is applied to detect the cancer of the urinary bladder or the diseases of the urinary system, wherein the liquid specimen 3 is urine. Normal urine (liquid specimen 3) contains none or only a trace of enzyme. Therefore, when the biosensor 2 detects normal urine, the change of the SAW characteristics is not obvious. When the bladder has a cancer or other diseases, the enzyme (analyte 4) is increased greatly. The great amount of the enzyme causes an obvious decrease of the physical quantity (mass) of the gelatin (test polymer 21) after reaction. Therefore, the present invention can be used to detect a urinary disease or cancer. Refer to
The embodiments described above are only to exemplify the present invention but not to limit the scope of the present invention. Any equivalent modification or variation according to the technical contents disclosed in the specification and drawings of the present invention is to be also included within the scope of the present invention.
