Application of Magnetic Ribbon Coated with Poly(3,4-ethylenedioxythiophene)/Poly(4-styrenesulfonate) to a Wireless Ammonia Sensor

Abstract

This paper describes a wireless ammonia sensor that employs the resonance frequency change in a curved magnetic ribbon coated with poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS). As PEDOT/PSS expands due to the sorption of ammonia molecules, the curvature of the ribbon is decreased with increasing ammonia concentration, Pam. The decrease in curvature reduces the mechanical resonance frequency from 105 kHz at Pam = 0% to 89 kHz at Pa= 10%. We also confirmed that the resonance frequency is proportional to the curvature and that the proportional constant is 0.33 kHz/m -1 . Since the mechanical vibration of the ribbon is excited by applying AC and DC fields and is detected by monitoring the voltage induced on a pickup coil, the Pam value around the ribbon can be detected wirelessly.