RESIST-FREE SOFT FABRICATION OF SILK ELECTRODE SENSORS: PAVING THE WAY FOR FLEXIBLE ELECTRONICS ON SILK
Anoop Patil1,2, Lun-De Liao1,2, John Ho1,2, Toh Siew Lok1, Yen Shih-Cheng1,2, Nitish Thakor1,2,3
1National University of Singapore, Singapore;
2Singapore Institute for Neurotechnology, Singapore;
3Johns Hopkins University, USA
We demonstrate, for the first time, silk bioelectronic sensors based on thin nontransient silk fibroin films with selectively exposed metal contacts capable of sensing minute electrical changes in a physiological environment. The sensors are fabricated using SILKSEAL, a new resist-free procedure based on micromolding, stamping, and gluing that enables precisely patterned insulating silk films to be integrated with metallized silk substrates in a multilayer silk device. This is a first-of-its-kind effort to design an excellently biocompatible and sustainable film-based silk fibroin device, with an ultrathin metal deposit sandwiched between two thin silk layers serving as the conductive layer facilitating electrical sensing in a physiological medium. Impedance measurements under accelerated soak demonstrate the stability of the silkbased sensors. In vitro recording experiments serve as evidence for the potential use of this technology in implantable biosensing applications. Furthermore, the silk interfaces are flexible and are found to be conformal to the challenging non-planar geometries as demonstrated by the deployment of silk sensors on various tissue surfaces. The concepts reported here provide a platform for designing advanced multilayer bioelectronic devices on silk.