Highly conductive film of PEDOT:PSS treated with cosolvent of formamide and methanol for flexible piezoresistive sensor applications

Flexible and wearable piezoresistive sensors keep attracting attention in many areas due to their wide application. Flexible materials with high conductivity are crucial to be explored for flexible piezoresistive sensors. In this work, a mild treatment method utilizing a cosolvent of formamide and methanol to dramatically improve the film conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was developed. The PEDOT:PSS film conductivity was improved from 0.3 to 1287 S/cm through double treatments with cosolvent of formamide and methanol. The enhancement of conductivity is because of reduced insulating PSS and the change of PEDOT chain conformational. The flexible piezoresistive sensor made by the formamide/methanol treated PEDOT:PSS film demonstrates good performance, especially the excellent mechanical durability in detecting finger joint movement, which suggests that the sensor developed has promising application in human motion detection.