Patent Publication Number: US-2020300773-A1

Title: Colorimetric sensor chip for gas sensing

Description:
FIELD OF THE INVENTION 
     The present invention relates to a sensor chip, and more particularly to a light, thin and highly integrated colorimetric sensor chip. 
     BACKGROUND OF THE INVENTION 
     In recent years, gas sensing devices used to detect the flow rate and type of gas become thinner and lighter. The dimensions of the gas sensing devices have been greatly reduced to less than 1 cm in the form of chip, and the integration with other devices has also been greatly improved. However, such a type of gas sensing chip integrated with other devices has a complicated structure, and usually includes a plurality of sensor arrays internally. Although the electric current transmission of each of the sensors in the array is controlled independently according to the current semiconductor technology, and the problem of the bus is solved, the drawbacks of high temperature and large power consumption still need to be overcome. 
     Another type of gas sensing device has a relatively simple structure. For example, the Taiwan patent no. 1374265 mentions a gas sensor, which includes a planar inductance-capacitance resonator and a gas absorbing material. The planar inductance-capacitance resonator includes an inductance electrode and a capacitance electrode, and the capacitance electrode is connected to the inductance electrode. The gas absorbing material is connected to at least a part of the capacitance electrode. Through the above structure, the gas absorbing material changes the resonance frequency of the planar inductance-capacitance resonator according to a change in the concentration of a gas to be tested, and then the change in the concentration of the gas to be tested is known. 
     However, such a type of gas sensing device still needs to rely on power supply, so the applicable range is relatively limited. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to solve the drawbacks of high temperature and large power consumption of the conventional energized gas sensing chips during operation, and the application field is restricted since the conventional energized gas sensing chips must require power supply during the measurement. Another object of the present invention is to provide a light, thin and highly integrated gas sensing chip. 
     In order to achieve the above objects, the present invention provides a colorimetric sensor chip including a chemical reaction layer and a coloring reaction layer. The chemical reaction layer includes at least one reaction zone reacting with a gas to be tested to produce a chemical change, and one side of the chemical reaction layer opposite to the coloring reaction layer is an air inlet side. The coloring reaction layer includes a coloring side and a reaction side opposite to each other, the reaction side contacts with the reaction zone of the chemical reaction layer. The coloring reaction layer includes a coloring indicator to produce a coloring reaction corresponding to the chemical change of the reaction side. 
     Accordingly, the colorimetric sensor chip of the present invention reacts with the gas to be tested through the reaction zones disposed on the chemical reaction layer, and then undergoing the chemical change. The chemical change shows different colors through the reaction of the coloring indicator of the coloring reaction layer. Users judge the colors with an existing database or through digitization. In this way, the colorimetric sensor chip of the present invention completes gas sensing without consuming electric power. Besides, the colorimetric sensor chip performs real-time sensing by directly attaching or placing on an object to be sensed due to its simple, light and thin structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a first embodiment of a colorimetric sensor chip of the present invention; 
         FIG. 2  is a schematic diagram of a second embodiment of the colorimetric sensor chip of the present invention; 
         FIG. 3  is a schematic diagram of a third embodiment of the colorimetric sensor chip of the present invention; 
         FIG. 4  is a schematic diagram of a fourth embodiment of the colorimetric sensor chip of the present invention; 
         FIG. 5  is a schematic diagram of a fifth embodiment of the colorimetric sensor chip of the present invention; 
         FIG. 6  is a schematic diagram of a sixth embodiment of the colorimetric sensor chip of the present invention; 
         FIG. 7  is a schematic diagram of a coloring side of the colorimetric sensor chip of the present invention; 
         FIG. 8  is a schematic diagram of a method for manufacturing the colorimetric sensor chip according to an embodiment of the present invention; and 
         FIG. 9  is a schematic diagram of a method for manufacturing the colorimetric sensor chip according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The detailed description and technical contents of the present invention are described below with reference to the drawings. 
       FIG. 1  is a schematic diagram of a first embodiment of a colorimetric sensor chip. The colorimetric sensor chip mainly includes a chemical reaction layer  10 , a coloring reaction layer  20  stacked with the chemical reaction layer  10 , and a plurality of partition portions  30 . 
     In this embodiment, the chemical reaction layer  10  is divided into a plurality of first areas by the partition portions  30 , wherein the first areas  11   a ,  11   b  marked in  FIG. 1  are only used as an example for illustration in the embodiment. The first areas  11   a ,  11   b  respectively include air inlet sides  12   a ,  12   b  disposing on sides opposite to coloring reaction layer  20 , and reaction zones  13   a ,  13   b . A gas to be tested G enters into the reaction zones  13   a ,  13   b  through the air inlet sides  12   a ,  12   b , and the reaction zones  13   a ,  13   b  react with the gas to be tested G to produce a chemical change. The reaction zones  13   a ,  13   b  respectively includes different kinds of chemicals to react with the different gases to be tested G. For example, some of the reaction zones  13   a ,  13   b  react with alkanes, some of the reaction zones  13   a ,  13   b  react with alcohols, and some of the reaction zones  13   a ,  13   b  react with sulfides. The partition portions  30  separate the adjacent first areas  11   a ,  11   b  so that reactions occurring in the adjacent first areas  11   a ,  11   b  do not affect each other. The chemical change is produced by a redox reaction, an acid-base reaction, an enzyme-catalytic reaction, a metal-catalytic reaction, a condensation reaction, a hydrolysis reaction, an addition reaction, an elimination reaction, a substitution reaction, or combinations of the above, but is not limited thereto. For example, one suitable redox reaction for the present invention could be the oxidizing ethanol to acetaldehyde or acetic acid, and a glucose oxidase is used in enzyme-catalytic reaction, and a platinum catalyst is used in metal catalyst. 
     In this way, assuming that one of the reaction zones  13   a ,  13   b  is coated with hydrazine (H 2 N—NH 2 ), carbazic acid (H 2 NNHCOOH) is produced when the gas to be tested G containing carbon dioxides reacts with the reaction zones  13   a ,  13   b  coated with hydrazine, and color is generated by using crystal violet as a redox indicator. Also, in an embodiment, the colorimetric sensor chip further includes a protective layer (not shown in the figure) disposed on the air inlet sides  12   a ,  12   b  to prevent gas from directly entering the reaction zones  13   a ,  13   b  to cause interference or damage. 
     The coloring reaction layer  20  is also divided into a plurality of second areas by the partition portions  30 , wherein the second areas  21   a ,  21   b  marked in  FIG. 1  are only used as an example for illustration in the embodiment. The second areas  21   a ,  21   b  and the first areas  11   a ,  11   b  are stacked with each other, and the second areas  21   a ,  21   b  include coloring sides  22   a ,  22   b  respectively, and reaction sides  23   a ,  23   b  respectively contact with the reaction zones  13   a ,  13   b  of the chemical reaction layer  10 . The coloring reaction layer  20  includes a coloring indicator; therefore, when the chemical change is produced in the reaction zones  13   a ,  13   b  due to chemical reactions, the coloring reaction layer  20  in contact with the reaction zones  13   a ,  13   b  produces a coloring reaction corresponding to the chemical change. 
     In this embodiment, the partition portion  30  is a partition wall that separates the adjacent first areas  11   a ,  11   b  and the second areas  21   a ,  21   b , so that the reaction zone  13   a  will not affect the adjacent reaction zone  13   b  when the gas to be tested G enters through the air inlet side  12   a  to react with the reaction zone  13   a . Likewise, reactions occurred in the reaction zone  13   a  will only affect the reaction side  23   a  and the coloring side  22   a , but will not affect the reaction side  23   b  and the coloring side  22   b . In addition, in this embodiment, the chemical reaction layer  10  and the coloring reaction layer  20  are a double-layer structure independent of each other. However, in other embodiments, the chemical reaction layer  10  and the coloring reaction layer  20  are a single-layer structure, that is, the chemical reaction layer  10  and the coloring reaction layer  20  are integrated into a single layer. 
     Compositions of the coloring indicator are selected from a group consisting of a hydrate, a precipitate, a metal complex, and combinations thereof. Take the hydrate as an example, it can be pink hydrate produced when dry cobaltous chloride meets water vapor; take the precipitate as an example, it can be black lead sulfide precipitate produced when lead acetate meets hydrogen sulfide; take the metal complex as an example, it can be oxygen coordinating and combining with iron ions in heme to present bright red color. The “coloring indicator” suitable for use in the present invention is not particularly limited. For example, the coloring indicator is further an acid-base indicator, a solvatochromism, or combinations thereof. For instance, the acid-base indicator suitable for use in the present invention is not particularly limited. In an embodiment, the acid-base indicator is a coloring reagent such as Bromothymol Blue, or phenolphthalein, and the like. 
     Further, please refer to  FIG. 2  for a schematic diagram of a second embodiment of the colorimetric sensor chip. Compared with the first embodiment described above, the second embodiment further includes an anti-reflection film  40  disposed on the coloring sides  22   a ,  22   b . The anti-reflection film  40  helps users to observe changes in color of the coloring sides  22   a ,  22   b  from outside through an instrument or the naked eye without interference. 
     Further, please refer to  FIG. 3 , in a third embodiment of the colorimetric sensor chip, an air-permeable film  50  with water-blocking property is disposed to reduce the interference of the external environment to the internal chemical reactions, and the air-permeable film  50  is disposed on the air inlet sides  12   a ,  12   b  of the chemical reaction layer  10 . In  FIG. 3 , the air-permeable film  50  is provided based on the structure of the second embodiment shown in  FIG. 2 . In another embodiment, the air-permeable film  50  is provided based on the structure of the first embodiment without limitation. 
     In  FIG. 4 , a diffusion film  60  is provided based on the structure of the third embodiment shown in  FIG. 3 . In a fourth embodiment shown in  FIG. 4 , at least one layer of diffusion film  60  with gas screening function is sandwiched between the air-permeable film  50  and the chemical reaction layer  10  to achieve the effect of screening specific gases. Moreover, gases targeted by each of the diffusion films  60  are different from each other when the diffusion films  60  are provided. In addition, each of the diffusion films  60  is added with graphenes  70  to adjust the diffusion path of gases in the diffusion films  60 , thereby changing the diffusion speeds of large and small molecules to obtain the effect of screening large and small molecules. 
     In addition, the colorimetric sensor chip further includes an adsorption molecule (not shown in the figures) in the diffusion film  60  to adsorb gas molecules more efficiently. The adsorption molecule is selected from any liquid, colloid, hole, or fiber film with adsorption function. In an embodiment, glycerin is used as the adsorption molecule; or in an embodiment, holes are used as the adsorption molecule to screen out larger-sized gas molecules by its characteristics. However, in another embodiment, as shown in  FIG. 5 , an adsorption layer  80  containing adsorption molecules is directly disposed between a pair of the diffusion films  60 , thereby having good adsorption effect. 
     Further, please refer to  FIG. 6  for a schematic diagram of a sixth embodiment of the colorimetric sensor chip, the structure of the sixth embodiment is provided based on the structure of the first embodiment. At least one diffusion film  60  with gas screening function is directly formed on the air inlet sides  12   a ,  12   b  of the chemical reaction layer  10 , and the diffusion film  60  is selectively provided with the graphenes  70  to adjust the diffusion path of gases in the diffusion films  60 . The materials and functions of the film layers in this embodiment are the same as the embodiments described above, and will not be described in detail. 
     Further, please refer to  FIG. 7 , in this embodiment, the colorimetric sensor chip shown in  FIG. 1  is fixed on a carrier  90 , wherein the carrier  90  is a sticker, and a plurality of colorimetric blocks  24  corresponding to the first areas  11   a ,  11   b  and the second areas  21   a ,  21   b  are formed on the carrier  90 . In this embodiment, the colorimetric block  24  includes a plurality of first colorimetric blocks  241   a ,  241   b  and a plurality of second colorimetric blocks  242   a ,  242   b . The first colorimetric blocks  241   a ,  241   b  and the second colorimetric blocks  242   a ,  242   b  have different colors, such as red and yellow, and the first colorimetric blocks  241   a ,  241   b  are red with different color ramps respectively, the second colorimetric blocks  242   a ,  242   b  are yellow with different color ramps respectively. The colorimetric blocks  24  shown in  FIG. 7  are merely illustrative, and are not intended to limit the present invention. Further, in this embodiment, the carrier  90  is further provided with a two-dimensional QR image code  91  and a label  92 . 
       FIG. 8  and  FIG. 9  are respectively schematic diagrams of methods for manufacturing the colorimetric sensor chip of the present invention, wherein  FIG. 8  is a “bottom up” method, and 
       FIG. 9  is a “top down” method. 
     The method shown in  FIG. 8  firstly uses a test paper  100  as a substrate (step  1 - 1 ), and pretreatment is performed on one side of the test paper  100  to separate into a plurality of blocks  101  that do not affect each other. Subsequently, the coloring reaction layer  20  and the chemical reaction layer  10  are titrated sequentially on one of the blocks  101  and are dried to form a sensing portion  102   a  (step  1 - 2 ). The sensing portion  102   a  includes the coloring reaction layer  20  and the chemical reaction layer  10  mentioned above. Then, sensing portions  102   b ,  102   c , and  102   d  with different compositions are formed on the adjacent blocks  101  respectively (step  1 - 3 ). The manufacturing method of the colorimetric sensor chip shown in  FIG. 8  is merely illustrative, and is not intended to limit the present invention. According to the different embodiments, at least one layer of the diffusion film  60  with gas screening function and/or the adsorption layer  80  is disposed on the chemical reaction layer  10  by titration-drying method; the air-permeable film  50  with water-blocking property is also formed on the top; the anti-reflection film  40  is attached on one side of the test paper  100  that has not been pretreated. 
       FIG. 9  provides another manufacturing method. Firstly, four test papers  200   a ,  200   b ,  200   c , and  200   d  are provided (step  2 - 1 ). The test papers  200   a ,  200   b ,  200   c , and  200   d  respectively have a plurality of blocks  201   a ,  201   b ,  201   c ,  201   d  that do not affect each other. Then, a plurality of sensing portions  202   a ,  202   b ,  202   c ,  202   d  with different compositions are formed on the blocks  201   a ,  201   b ,  201   c ,  201   d  respectively (step  2 - 2 ). The sensing portions  202   a ,  202   b ,  202   c ,  202   d  respectively include the coloring reaction layer  20  and the chemical reaction layer  10  described above. Subsequently, cut the test papers  200   a ,  200   b ,  200   c , and  200   d  to remove the sensing portions  202   a ,  202   b ,  202   c ,  202   d  respectively, and combine the sensing portions  202   a ,  202   b ,  202   c ,  202   d  with a base plate  300  (step  2 - 3 ) to dispose the sensing portions  202   a ,  202   b ,  202   c ,  202   d  on the base plate  300  (step  2 - 4 ). In step  2 - 5 , repeat step  2 - 3  and step  2 - 4  to obtain a colorimetric sensor chip finally (step  2 - 6 ). According to different modes of the embodiment, if necessary, at least one layer of the diffusion film  60  with gas screening function and/or the adsorption layer  80  is provided on the chemical reaction layer  10 . The manufacturing method of the colorimetric sensor chip shown in  FIG. 9  is merely illustrative, and is not intended to limit the present invention. According to the different embodiment, depending on the requirements, the air-permeable film  50  is attached on the air inlet sides  12   a ,  12   b , and the anti-reflection film  40  is attached on the coloring sides  22   a ,  22   b.    
     Accordingly, when the colorimetric sensor chip is used to identify whether a meat to be tested is deteriorated, the meat to be tested and the colorimetric sensor chip are placed in a closed environment simultaneously for a period of time, and an odor (such as ammonia) emitted by the meat to be tested enters through the air inlet sides  12   a ,  12   b  of the chemical reaction layer  10  and reacts with the reaction zones  13   a ,  13   b  to produce a chemical change. Subsequently, the reaction sides  23   a ,  23   b  of the coloring reaction layer  20  contact the reaction zones  13   a ,  13   b  of the chemical reaction layer  10 , so that the coloring indicator contained in the coloring reaction layer  20  shows a specific color corresponding to the chemical change. Therefore, users judge the quality of the meat to be tested through the coloring sides  22   a ,  22   b  by their naked eye or machine. The meat to be tested has deteriorated if the color of the meat to be tested is the same as the color shown by the deteriorated meat in a previous database. Alternatively, users can further perform color correction and compare with a calibration curve so that users obtain an ammonia concentration to judge the quality of the meat to be tested by conversion.