Polymer toughness is preserved at chronic timepoints in a new class of modulus-changing bioelectronics, which hold promise for commercial chronic implant components such as spinal cord stimulation leads. The underlying ester-free chemical network of the polymer substrate enables device rigidity during implantation, soft, compliant, conforming structures during acute phases in vivo, and gradual stabilization of materials properties chronically, maintaining materials toughness as device stiffness changes. In the past, bioelectronics device designs generally avoided modulus-changing and materials due to the difficulty in demonstrating consistent, predictable performance over time in the body. Here, the acute, and chronic mechanical and chemical properties of a new class of ester-free bioelectronic substrates are described and characterized via accelerated aging at elevated temperatures, with an assessment of their underlying cytotoxicity. Furthermore, spinal cord stimulation leads consisting of photolithographically-defined gold traces and titanium nitride (TiN) electrodes are fabricated on ester-free polymer substrates. Electrochemical properties of the fabricated devices are determined in vitro before implantation in the cervical spinal cord of rat models and subsequent quantification of device stimulation capabilities. Preliminary in vivo evidence demonstrates that this new generation of ester-free, softening bioelectronics holds promise to realize stable, scalable, chronically viable components for bioelectronic medicines of the future.

在新型模量变化生物电子学中，聚合物的韧性在长期时间点得以保留，这为脊髓刺激导线等商业慢性植入组件带来了希望。聚合物基材的底层无酯化学网络使设备在植入过程中具有刚性，在体内急性期具有柔软、顺应性、适形的结构，并且材料性能长期逐渐稳定，在设备刚度变化时保持材料的韧性。过去，生物电子器件设计通常避免模量变化和材料，因为随着时间的推移很难在体内展示一致、可预测的性能。在这里，通过在高温下加速老化来描述和表征一类新型无酯生物电子基板的急性和慢性机械和化学特性，并评估其潜在的细胞毒性。此外，由光刻定义的金线和氮化钛（TiN）电极组成的脊髓刺激引线是在无酯聚合物基板上制造的。在植入大鼠模型的颈髓之前，在体外确定所制造的装置的电化学特性，并随后对装置刺激能力进行量化。初步体内证据表明，新一代无酯软化生物电子学有望为未来的生物电子药物实现稳定、可扩展、长期可行的组件。