Science 340, 211–216 (2013)

The continuous efforts in understanding brain physiology are driving the development of implantable tools with the ever-improving capability of stimulating and recording neuronal activity, and that have a reduced risk of causing tissue lesions. Kim et al. have now demonstrated a soft multifunctional device integrating platinum microelectrodes, temperature sensors, photodetectors and novel micrometre-scaled light-emitting diodes on a mechanically compliant polymeric substrate, suited for in vivo implantation in mice. To facilitate placement in deep regions of the brain, this tool is first attached by means of a silk-based glue to a stiff microneedle; then, the biodegradable adhesive is removed and the rigid support is released, thus minimizing the mechanical mismatch between the chronically implanted part and the surrounding tissues. The device is finally connected to a wireless antenna, which enables bidirectional communication of stimuli and data without limiting the movements of the mouse during optogenetic experiments. The authors predict that the performance stability, demonstrated over several months, will accelerate the use of these devices in clinical research studies.