Highly stretchable polystyrene sulfonate organic electrochemical transistors achieved via polyethylene glycol addition

Organic electrochemical transistors (OECTs) are widely used in biosensing and bioelectronics, due to their ability to convert ionic signals into electronic signals and their high transconductance. Stretchable OECTs are particularly suited for on-skin and on-organ bioelectronics, since they are able to record or transmit signals under mechanical strain. Most stretchable OECTs are based on the conducting polymer poly(3, 4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS), which needs to be appropriately processed to yield stretchable films. Here we report stretchable OECTs that are obtained by modifying the mechanical properties of PEDOT:PSS films via the addition of low-molecular weight polyethylene glycol (PEG), which acts as a plasticizer. The presence of PEG in the films prevents the formation of cracks under strain while maintaining a high electrical conductivity, thus resulting in improved electromechanical properties. In particular, the additon of PEG leads to a higher channel thickness and increased ion mobility in the films, thus resulting in stretchable OECTs with high transconductance and fast response time. This work shows that high stretchability, high transconductance and fast repsonse time can be simultaneously obtained in OECTs, paving the way for their applications in conformable devices at the human-machine interface.

有机电化学晶体管（OECTs）因其能够将离子信号转换为电子信号以及具有高跨导的特性，在生物传感和生物电子学中得到了广泛应用。可拉伸的OECTs特别适用于皮肤和器官上的生物电子学，因为它们能够在机械应变下记录或传输信号。大多数可拉伸的OECTs基于掺杂聚苯乙烯磺酸盐的导电聚合物聚（3,4 - 乙烯二氧噻吩）（PEDOT:PSS），需要对其进行适当处理以获得可拉伸薄膜。在此我们报道了通过添加低分子量聚乙二醇（PEG）作为增塑剂来改变PEDOT:PSS薄膜的机械性能而获得的可拉伸OECTs。薄膜中PEG的存在可防止在应变下形成裂纹，同时保持高导电性，从而使机电性能得到改善。特别是，PEG的添加使薄膜中的沟道厚度增加以及离子迁移率提高，从而得到具有高跨导和快速响应时间的可拉伸OECTs。这项工作表明，在OECTs中可以同时实现高拉伸性、高跨导和快速响应时间，为其在人机界面的贴合设备中的应用铺平了道路。