Using polypyrrole as the contrast ph detector to fabricate a whole solid-state ph sensing device

Abstract

A process for fabricating a whole solid-state pH sensing device by using the polypyrrole as the contrast pH detector and a whole solid-state pH sensing device fabricated by the process are disclosed, wherein said device is a differential pair framework potential electrochemical sensing device fabricated by using a non-insulating solid-state inorganic ion-sensing membrane and a polypyrrole sensing membrane. The differential pair framework uses tin dioxide as the ion-sensing membrane and the reference electrode, and uses a polypyrrole sensor as the differential sensor so that the sensing device framework has practicability. Since the sensitivity of the polypyrrole can be controlled by means of its polymerization, a sensing device with controllable sensitivity can be fabricated for applying to the fabrication of a pH sensor or a biosensor.

1 . A process for fabricating a whole solid-state pH sensing device by using polypyrrole as the a contrast pH detector, said process comprising the following steps:
 step 1: preparing various solid-state substrates and selecting an appropriate substrate based on a solid-state sensing material and a sensing environment;   step 2: depositing the solid-state sensing material on said substrate;   step 3: positioning the device;   step 4: using an epoxy resin to seal the material and fixing a sensing window area; and   step 5: then immersing the device into a an electro electro-polymerizing solution, and electro-polymerizing by using the polypyrrole, thus for completing the fabrication of the whole solid-state pH sensing device, wherein
 the step of electro-polymerizing the polypyrrole further comprises the following steps: 
 step A: preparing a finished conductive substrate; 
 step B: cleaning the substrate; 
 step C: preparing said electro-polymerizing solution, which comprises a buffer solution, electrolytes, and the monomer of polypyrrole; 
 step D: connecting the substrate to a positive electrode of a power supply, and connecting a platinum electrode to a negative electrode of the power supply, and immersing the substrate into said electro-polymerizing solution, where the power supply provides a constant potential which is higher than the oxidizing potential of said polypyrrole, in a manner that said polypyrrole polymerized on said substrate; 
 step E: immersing a polypyrrole sensor into de-ionized water for ten (10) minutes to clean said polypyrrole sensor; 
 step F: removing and drying said sensing device, thus completing fabrication of the polypyrrole sensor; 
   said solid-state substrate is selected from the group consisting of a silicon substrate, a glass substrate, a ceramic substrate and a plastic substrate;   said sensing material is selected from the group consisting of a tin dioxide membrane and other solid-state conductive ion-sensing membrane; and   said polymerizing solution comprises a buffer solution, salts, and polypyrrole, the polymerizing solution comprising a phosphate solution, potassium chloride, and polypyrrole; wherein, through changing the composition of said polymerizing solution, the control of the sensitivity of said polypyrrole sensor is achieved, and wherein the process is applied to fabricate a sensing electrode with an appropriate sensitivity and the control of the sensitivity of a differential pair pH sensing device is obtained.   
   
   
       2 . A process for fabricating a whole solid-state pH sensing device by using polypyrrole as a contrast pH detector, said process comprising the following steps:
 step 1: preparing various solid-state substrates and selecting an appropriate substrate based on a solid-state sensing material and a sensing environment;   step 2: depositing the solid-state sensing material on said substrate;   step 3: positioning the device;   step 4: using an epoxy resin to seal the material and fixing a sensing window area; and   step 5: immersing the device into an electro-polymerizing solution and electro-polymerizing the polypyrrole for completing the fabrication of the whole solid-state pH sensing device, wherein
 the step of electro-polymerizing the polypyrrole comprises the following steps: 
 step A: preparing a finished conductive substrate; 
 step B: cleaning the substrate; 
 step C: preparing said electro-polymerizing solution, which comprises a buffer solution, electrolytes, and the monomer of polypyrrole; 
 step D: connecting the substrate to a positive electrode of a power supply, and connecting a platinum electrode to a negative electrode of the power supply, and immersing the substrate into said electro-polymerizing solution, where the power supply provides a constant potential which is higher than the oxidizing potential of said polypyrrole, in a manner that said polypyrrole polymerized on said substrate; 
 step E: immersing a polypyrrole sensor into de-ionized water for ten (10) minutes to clean said polypyrrole sensor; 
 step F: removing and drying said sensing device, thus completing fabrication of the polypyrrole sensor; 
   said solid-state substrate is selected from a plastic substrate;   said sensing material is selected from the group consisting of a tin dioxide membrane and other solid-state conductive ion-sensing membrane;   said between sensing material and solid-state substrate, there is a carbon layer for conduct electrons; and   said polymerizing solution comprises a buffer solution, salts, and polypyrrole, the polymerizing solution comprising a phosphate solution, potassium chloride, and polypyrrole; wherein, through changing the composition of said polymerizing solution, the control of the sensitivity of said polypyrrole sensor is achieved, and wherein the process is applied to fabricate a sensing electrode with an appropriate sensitivity and the control of the sensitivity of a differential pair pH sensing device is obtained.