Development of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate/Triton X-100-conductive hydrogels for bioelectronic applications

Conductive hydrogels based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are widely used in bioelectronics because they combine printability with good electrical conductivity. However, their brittle nature restricts their durability, especially in implantable devices that must bend, stretch, and remain reliable over time. A key challenge is therefore to create hydrogels that are both mechanically compliant and electrochemically stable.

In this work, we describe a simple design strategy using Triton X-100, a common surfactant, as a plasticizer for lyophilized PEDOT:PSS hydrogels. Mechanical testing showed that plasticization significantly reduced stiffness and viscosity, while elongation at break more than doubled and fracture strength increased. Together, these improvements converted a fragile material into a tough, flexible, and stretchable conductor. Importantly, the electrical function of the hydrogel was largely preserved.

To evaluate device performance, the plasticized hydrogel was integrated into a polydimethylsiloxane (PDMS) encapsulation mimicking an electrode contact. Cyclic voltammetry remained stable with no significant unwanted redox reactions. Impedance spectroscopy revealed only a small increase at 1 kHz, consistent with fewer electron pathways, but this trade-off was minor compared with the substantial mechanical gains.

Overall, this study shows that simple plasticizer additives can tune the balance between mechanics and conductivity. By achieving softness, toughness, and electrochemical reliability in the same material, this strategy moves PEDOT:PSS hydrogels closer to long-term use in bioelectronic interfaces.