Highly conductive,stretchable,durable,skin-conformal dry electrodes based on thermoplastic elastomer-embedded 3D porous graphene for multifunctional wearable bioelectronics

Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchability and low flexibility of PI films.As a result,high interface impedance and motion artifacts can occur during body movements.Transferring LIG to flexible substrates such as polydimethylsiloxane(PDMS)and Ecoflex allows for stretchability and flexibility.However,the transfer process produces a significant loss of conductivity destroying the structural function and electron conduction properties of the LIG.We found robust physical and chemical bonding effects between LIG and styrene-ethylene-butylene-styrene(SEBS)thermoplastic elastomer substrates and proposed a simple and robust low-conductivity loss transfer technique.Successfully embedded LIG onto SEBS to obtain high stretchability,high flexibility,low conductivity losses.Electrophoretic deposition(EPD)of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid(PEDOT:PSS)on LIG forms an ultrathin polymer conductive coating.The deposition thickness of the conductive polymer is adjusted by controlling the EPD deposition time to achieve optimal conductivity and chemical stability.SEBS/LIG/PEDOT:PSS(SLPP)dry electrodes have high conductivity(114Ω/Sq),stretchability(300%)and reliability(30%stretch,15,000 cycles),low electrode-skin impedance(14.39 kΩ,10 Hz).The detected biopotential signal has a high signal-to-noise ratio(SNR)of 35.78 dB.Finally,the feasibility of SLPP dry electrodes for long-term biopotential monitoring and biopotential-based human-machine interface control of household appliances was verified.