Digital selective transformation and patterning of highly conductive hydrogel bioelectronics by laser-induced phase separation

Abstract

The patterning of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hydrogels with excellent electrical property and spatial resolution is a challenge for bioelectronic applications. However, most PEDOT:PSS hydrogels are fabricated by conventional manufacturing processes such as photolithography, inkjet printing, and screen printing with complex fabrication steps or low spatial resolution. Moreover, the additives used for fabricating PEDOT:PSS hydrogels are mostly cytotoxic, thus requiring days of detoxification. Here, we developed a previously unexplored ultrafast and biocompatible digital patterning process for PEDOT:PSS hydrogel via phase separation induced by a laser. We enhanced the electrical properties and aqueous stability of PEDOT:PSS by selective laser scanning, which allowed the transformation of PEDOT:PSS into water-stable hydrogels. PEDOT:PSS hydrogels showed high electrical conductivity of 670 S/cm with 6-μm resolution in water. Furthermore, electrochemical properties were maintained even after 6 months in a physiological environment. We further demonstrated stable neural signal recording and stimulation with hydrogel electrodes fabricated by laser.

PEDOT and PEDOT:PSS thin-film electrodes: patterning, modification and application in stretchable organic optoelectronic devices

“…In recent work, Won et al 63 implemented ultrafast digital patterning of highly conductive PEDOT:PSS films via a laser-induced phase separation (LIPSP) technique (Fig. 3(b)).…”

Transparent Electronics for Wearable Electronics Application

“…However, developed conductive hydrogels are difficult to use as transparent biointerfacing electronics due to their low transparency which requires grid-patterning techniques. Various patterning methods to pattern conductive hydrogels are reported, but only several results showed relatively high resolutions of patterns. ,,, Conventional photolithography could fabricate the highest resolution of conductive hydrogels by incorporating UV-curable agents in polymer chains which succeed in sub 10 μm of line width . However, it required over 10 steps of complex fabrication flow with expensive vacuum systems.…”

Functional conductive hydrogels: from performance to flexible sensor applications

“…In addition, the fabrication of water-stable PEDOT:PSS hydrogels has been reported using a continuous-wave laser to provide strong electric fields and photothermal energy to induce phase separation of PEDOT:PSS on an ultrashort timescale. 200 A neural signal recording device was made by sandwiching hydrogel electrodes between thermoplastic polyurethane and PDMS. Treatment of mouse brain slices with stimulant drugs induces brain excitability in mice (Fig.…”