Yong Xu, an associate professor of electrical and computer engineering in the College of Engineering at Wayne State University (Detroit), has developed a silicon-on-insulator (SOI)–complementary-metal-oxide-semiconductor (CMOS) process for fabricating flexible electronics. As reported in Applied Physics Letters, the technology could eventually find its way into a range of wearable health monitoring devices and medical implants. The technology, Xu says, could perhaps be used to manufacture retinal prostheses, balloon catheters, and stents.
Several approaches to making flexible sensors and electronics cannot take full advantage of mainstream CMOS processes, according to Xu. In contrast, the new method fabricates high-performance, high-density CMOS circuits on SOI wafers and then uses two layers of the polymer Parylene C to bond the circuits to flexible substrates. The lamination of the electronics between the parylene layers protects the circuits from environmental moisture. A biocompatible material, Parylene C creates a flexible skin and has already has been used in medical device applications.
Xu’s process allows more high-performance electronic devices to be attached to the flexible surface by eliminating the transfer-printing step, in which electronics are removed from a harder surface and integrated into a softer one. His process also enables various sensors and microfluidic devices to be integrated into the flexible substrate.
“The ultimate goal is to develop flexible and stretchable systems integrated with electronics, sensors, microfluidics, and power sources, which will have a profound impact on personalized medicine, telemedicine, and healthcare delivery,” Xu comments.