Methods for stabilizing palladium films
The present disclosure relates to methods of creating a biosensor. A palladium film is deposited onto a surface of a substrate. The palladium film is then treated with an air plasma to stabilize the palladium and reduce or eliminate its catalytic activity. The biosensor is created from the treated palladium film and the substrate.
1. A method of creating a biosensor, comprising:
forming a first electrode used in a biosensor, comprising:
forming a palladium film on a surface of a substrate; and
treating a surface of the palladium film with an air plasma coating process to add a stabilizing film to the surface of the palladium film, resulting in the first electrode of a biosensor comprised of a treated palladium film of palladium film coated with the stabilizing film, wherein the air plasma coating process comprises:
using a flow of gas comprising about 78 vol % nitrogen and about 21 vol % oxygen, at a flow rate of about 2 sccm to about 1000 sccm;
applying a vacuum at a negative pressure of about 10 mTorr to about 200 mTorr;
applying power at about 1 W to about 20 kW; and
wherein the resulting stabilizing film has a contact angle that is substantially equivalent to a palladium film that has been aged in ambient conditions over 60 to 90 days.
2. The method of claim 1 , further comprising forming a reaction chamber on the substrate, the reaction chamber contacting the first electrode.
3. The method of claim 1 , further comprising forming a reagent layer on the treated palladium film so that the first electrode operates as a working electrode, the reagent layer comprising a selective recognition component for an analyte.
4. The method of claim 1 , wherein the first electrode operates as a reference electrode, and further comprising forming a second electrode on the substrate, and placing a reagent layer on the second electrode to form a working electrode, the reagent layer comprising a selective recognition component for an analyte.
5. The method of claim 1 , wherein the palladium film is treated with the air plasma at the power of 1 W to 3 kW.
6. The method of claim 1 , wherein the palladium film is treated with the air plasma using the gas flow of about 5 sccm to about 20 sccm.
7. The method of claim 1 , wherein the substrate is provided in the form of a web, and wherein the palladium film is treated with the air plasma at a web speed of about 1 ft/min to about 100 ft/min.
8. The method of claim 1 , wherein the palladium film is treated with the air plasma at the negative pressure of about 10 mTorr to about 20 mTorr.
9. The method of claim 1 , wherein a distance between the substrate and a plasma treatment source is about 1 inch to about 5 feet when the palladium film is treated with the air plasma.
10. The method of claim 1 , wherein the palladium film is treated with the air plasma at the power of about 1 kilowatt to about 5 kilowatts and using the gas flow of about 30 sccm to about 500 sccm, and the negative pressure of about 10 mTorr to about 20 mTorr.
11. The method of claim 1 , wherein the substrate is provided in the form of a web, and wherein the palladium film is treated with the air plasma at the power of about 1 watt to about 10 kilowatts and using at a web speed of about 1 ft/min to about 100 ft/min.
12. The method of claim 1 , wherein the palladium film is treated with the air plasma at the power of about 1 watt to about 10 kilowatts and using the negative pressure of about 10 mTorr to about 100 mTorr.
13. The method of claim 1 , further comprising coating the treated palladium film with 2-mercaptoethane sulfonate, resulting in a coated, treated palladium film.
14. The method of claim 1 , wherein the flow of gas comprising about 78 vol % nitrogen and about 21 vol % oxygen comprises a reactive gas, the air plasma coating process further comprising using a flow a working gas at a flow rate of about 2 sccm to about 1000 sccm, the working gas comprising argon.
15. The method of claim 1 , wherein the resulting stabilizing film has a thin complex O-C-H layer.
16. The method of claim 1 , wherein the resulting stabilizing film has a capacitance error that is substantially equivalent to a palladium film that has been aged in ambient conditions over 60 to 90 days.
17. The method of claim 1 , wherein the contact angle measures a surface energy that is consistent over time.
18. The method of claim 1 , wherein the resulting stabilizing film has catalytic activity that is substantially equivalent to a palladium film that has been aged in ambient conditions over 60 to 90 days.
19. The method of claim 1 , wherein the resulting stabilizing film has a stable and predictable electrical performance over time.
20. The method of claim 1 , wherein the resulting stabilizing film has a surface energy determined by cyclic voltammetry.