Polymer-based microelectronic pH-sensor

Abstract

Abstract Several types of new microelectronic devices including diodes, transistors, sensors, surface energy storage elements, and light-emitting devices are disclosed. The properties of these devices can be controlled by molecular-level changes in electroactive polymer components. These polymer components are formed from electrochemically polymerizable material whose physical properties change in response to chemical changes. Examples of such materials include polymers which respond to changes in redox potential. Very stable, polymer-based electrochemical devices which are durable in an aqueous electrolyte over a wide pH range and which respond rapidly to chemical or electrical signals are formed by polymerization of thiophene or a derivative such as 3-methylthiophene. In one embodi ment, the device functions as an extremely sensitive sensor which measures changes in chemical concentration or pH. For example. a poly-3-methylthiophene-based device is sensitive to as little as 8 x 10- 16 moles of an oxidant which reversibly interacts with the polymer, including gas phase oxidants such as I 2 . In a variation of the polymer-based device, a catalyst such as a noble metal or an enzyme is dispersed on or within the conducting polymer matrix so that the device is responsive to chemicals such as H 2 and O 2 which the polymer would otherwise respond very slowly to. In another embodiment, a polymer-based electrochromic device consists of individually adressable microelectrodes coated with a polymer whose optical properties change in response to chemical or electrical signals. Very high resolution is achieved by separating the microelectrodes by distances on the order of 10,000 Angstroms. In still another embodiment, the polymer-based device functions as a capacitor with an energy density as high as 200-300 J cm 3 which can operate at frequencies as high as 100 Hz when the device is formed from a polymer of thiophene or a thiophene derivative. These very small, specific, sensitive devices provide means for interfacing electrical and chemical systems while consuming very little power, and may be incorporated into conventional integrated circuit designs.

Inventors

• 👤 Mark S. Wrighton
• 👤 Henry S. White Jr.
• 👤 James W. Thackeray

Bibliographic Details