High-resolution micropatterning of a PEDOT:PSS conducting-polymer-silk-sericin composite is presented using a water-based, benchtop photolithographic process. Conducting microstructures formed on a flexible silk fibroin sheet allow a fully organic, flexible bioelectronic device. Large-area microfabricated devices such as biosensors that are biocompatible and degradable over a controlled period of time can be formed.