Optical transparent packages for implantable devices

We present a carbon dioxide (CO2) laser-assisted simultaneous localized fusion bonding and dicing technology on fused silica wafer. Direct bonding of fused silica wafer stacks results in an optically transparent package without introducing intermediate bonding layers. The temperature inside the package is maintained below 400 °C during the fabrication process to preserve complementary metal-oxide-semiconductor (CMOS)- compatibility. Such fused silica packages have many favorable features such as optical transparency for packaging micro-opto-electro-mechanical systems (MOEMS), biocompatibility and hermeticity for implantation applications, and transparency at radio frequencies for encapsulating electronics for wireless power and signal transmission. We applied this localized fusion bonding technology to encapsulate humidity sensors, evaluating the hermeticity and suggesting an implantation lifespan of over 70 years in the human body. Furthermore, we extended its application to vacuum packages and implantable tactile sensing systems to restore hand function for individuals with paralysis.