Tuning the Electromechanical Properties of PEDOT:PSS Films for Stretchable Transistors And Pressure Sensors

Abstract

Poly(3,4‐ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) based organic electrochemical transistors (OECTs) have been widely applied in bioelectronics because of their low power consumption, biocompatibility, and ability to convert ionic biological signals into electronic signals with high sensitivity. Here, the processing of PEDOT:PSS thin films on soft substrates is reported for stretchable OECT applications. Enhanced stretchability of PEDOT:PSS films on elastic substrates is obtained by synergistically reducing the film thickness and decreasing the baking temperature. The resultant films, together with ultrathin Au electrodes, enable the assembling of fully stretchable OECTs using conventional fabrication techniques, without prestretching the substrates. The stretchable OECTs maintain similar electrical characteristics within 30% applied strain. It is also demonstrated that brittle PEDOT:PSS films, which are not suitable for making stretchable OECTs, can be used for transparent pressure sensors.

Tailoring the Self‐Healing Properties of Conducting Polymer Films

“…For instance, it is still unclear how the healing process is affected by compounds added during PEDOT:PSS film processing to modify the film adhesion properties, such as crosslinkers, or by treatments carried out to increase the electrical conductivity, such as acid soaking. [ 23–31 ] Moreover, it is unclear if self‐healing properties extend to other forms of PEDOT containing counterions other than PSS, obtained by chemical or electrochemical polymerization. Such forms of PEDOT are of interest since in small dopants, such as para ‐toluene sulfonate (or tosylate, Tos), trifluoromethanesulfonate (or triflate, OTf), and ClO 4 − , lead to an enhanced electrical conductivity (>1000 S cm −1 ) due to a more compact PEDOT–PEDOT stack.…”

Freeze‐drying and mechanical redispersion of aqueous PEDOT:PSS

“…The most reasonable explanation here may be the variation in particle size of the PEDOT:PSS colloidal gel, despite other factors including molecular weight, degree of hydrolysis, and concentration of the polymers, as well as environmental factors such as solvent type, temperature, and pH. In addition, the heat‐induced winding of PEDOT:PSS molecular chains is considered to be one of the reasons for the higher viscosity of B‐PEDOT:PSS 34 . Besides, it is well known that the acidity of PEDOT:PSS is caused by the hydrolysis of excess PSS − chains, and the recovery of pH value proves that the drying process does not alter the component ratio and acidity of PSS − .…”

“…In addition, the heatinduced winding of PEDOT:PSS molecular chains is considered to be one of the reasons for the higher viscosity of B-PEDOT:PSS. 34 Besides, it is well known that the acidity of PEDOT:PSS is caused by the hydrolysis of excess PSS − chains, and the recovery of pH value proves that the drying process does not alter the component ratio and acidity of PSS − . The surface resistance decreased by 13 times for F-PEDOT:PSS and 30 times for B-PEDOT:PSS, therefore largest particles size distribution may be anticipated in B-PEDOT:PSS.…”

Ultrathin and Robust Micro–Nano Composite Coating for Implantable Pressure Sensor Encapsulation

“… 21 , 32 , 33 Biocompatible with human bodies. 16 , 34 − 36 Minimal effect on the sensor performances: the measurement error and sensitivity of the sensor should be almost intact after encapsulation. 2 , 22 , 37 − 41 …”