A SOI-CMOS compatible smart yarn technology

Smart yarns and intelligent textiles have been researched for quite some time. However, most smart yarns and textiles developed so far do not come with sophisticated functionalities due to the fact that silicon-based sensors and CMOS circuits cannot be seamlessly integrated. This paper reports a SOI-CMOS compatible technology to fabricate smart yarns, enabling the monolithic and invisible integration of CMOS and sensors. A tubular shaped parylene smart yarn with reinforcing PMDS core has been developed. Isotropic XeF₂ silicon etching and conformal parylene coating were used to form the outer shell and release the electronic/sensing components from a SOI wafer. PDMS cores were injected after the release to reinforce and strengthen the yarns. To prove the concept, silicon strain gauges and MOSFETs were first integrated.