Needle-Like Multifunctional Biphasic Microfiber for Minimally Invasive Implantable Bioelectronics.

Implantable bioelectronics has attracted significant attention in electroceuticals and clinical medicine for precise diagnosis and efficient treatment of target diseases. However, conventional rigid implantable devices face challenges such as poor tissue-device interface and unavoidable tissue damage during surgical implantation. Despite continuous efforts to utilize various soft materials to address such issues, their practical applications remain limited. Here, a needle-like stretchable microfiber composed of a phase-convertible liquid metal (LM) core and a multifunctional nanocomposite shell for minimally invasive soft bioelectronics is reported. The sharp tapered microfiber can be stiffened by freezing akin to a conventional needle to penetrate soft tissue with minimal incision. Once implanted in vivo where the LM melts, unlike conventional stiff needles, it regains soft mechanical properties, which facilitate a seamless tissue-device interface. The nanocomposite incorporating with functional nanomaterials exhibits both low impedance and the ability to detect physiological pH, providing biosensing and stimulation capabilities. The fluidic LM embedded in the nanocomposite shell enables high stretchability and strain-insensitive electrical properties. This multifunctional biphasic microfiber conforms to the surfaces of the stomach, muscle, and heart, offering a promising approach for electrophysiological recording, pH sensing, electrical stimulation, and radiofrequency ablation in vivo.

Synthesis and exceptional operational durability of polyaniline-inspired conductive ladder polymers.

Ladder-type structures can impart exceptional stability to polymeric electronic materials. This article introduces a new class of conductive polymers featuring a fully ladder-type backbone. A judicious molecular design strategy enables the synthesis of a low-defect ladder polymer, which can be efficiently oxidized and acid-doped to achieve its conductive state. The structural elucidation of this polymer and the characterization of its open-shell nature are facilitated with the assistance of studies on small molecular models. An autonomous robotic system is used to optimize the conductivity of the polymer thin film, achieving over 7 mS cm-1. Impressively, this polymer demonstrates unparalleled stability in strong acid and under harsh UV-irradiation, significantly surpassing commercial benchmarks like PEDOT:PSS and polyaniline. Moreover, it displays superior durability across numerous redox cycles as the active material in an electrochromic device and as the pseudocapacitive material in a supercapacitor device. This work provides structural design guidance for durable conductive polymers for long-term device operation.