Biocompatible sealant used for a wireless optogenetic microsystem

Master Bond EP21LVMed is a two-component epoxy formulation used for high performance bonding, sealing, coating, encapsulating and casting. It passes both the USP Class VI biocompatibility requirements as well as the ISO 10993-5 cytotoxicity specifications, making it suitable for applications where biocompatibility is necessary.

In the application described below, it is utilised as a sealant for the hermetic packaging of biocompatible devices, specifically as a wireless neural interface microsystem.

Researchers at Michigan State and Georgia Tech have developed an implantable, wirelessly-powered/controlled LED array that can modulate the activity of mouse neurons by using light. Previous approaches used surface light delivery systems, but these did not provide a sufficient light penetration depth into the brain. The reported micro-LED array provided deeper light penetration after implantation and contained microelectrodes that wirelessly recorded changes in the neural activity of mice upon illumination by the LED array.

The scientists used standard MEMS fabrication techniques to obtain their wireless micro-LED array, which precisely delivered light to the target neurons. A major concern of this approach was to ensure its biocompatibility after implantation. To ensure this, once all components of the device were assembled, the researchers applied a thick layer (200–500 µm) of biocompatible EP21LVMed, which was then wrapped in Parylene-C. Master Bond’s recommended curing schedule for EP21LVMed is an overnight cure at room temperature, followed by around 2–3 hours at 150–200°F.

To learn the results of this experiment, we invite you to download the full case study here.