Monolithic Solder-on Nanoporous Si-Cu Contacts for Stretchable Silicone Composite Sensors

Abstract

We report a method of creating solderable, mechanically robust, electrical contacts to interface (soft) silicone-based strain sensors with conventional (hard) solid-state electronics using a nanoporous Si-Cu composite. The Si-based solder-on electrical contact consists of a copper-plated nanoporous Si top surface formed through metal-assisted chemical etching and electroplating, and a smooth Si bottom surface which can be covalently bonded onto silicone-based strain sensors through plasma bonding. We investigated the mechanical and electrical properties of the contacts proposed under relevant ranges of mechanical stress for applications in physiological monitoring and rehabilitation. We also produced a series of proof-of-concept devices, including a wearable respiration monitor, leg band for exercise monitoring and Squeeze-ball for monitoring rehabilitation of patients with hand injuries or neurological disorders, to demonstrate the mechanical robustness and versatility of the technology developed, in real-world applications.

Ultra-Low-Cost Integrated Silicon-based Transducer for On-Site, Genetic Detection of Pathogens

“…The wafer is then placed inside an etching bath containing an aqueous solution of H2O2 and HF with a ratio of 1:20 v/v (30% H2O2: 10% HF) to perform metalassisted chemical etching (MACE) of Si for 10 min. [17][18][19] This process forms a 500 nm thick nanoporous Silicon (pSi) layer on each side of the wafer (Figure 2A). pSi plays a critical role in the fabrication of TriSilix.…”

“…Without this step, the metal films electroplated do not adhere to the surface of the substrate. 19 The pSi layer also allows thermal bonding of sheets of polymer films in an ordinary heat press after patterning through laser-cutting ( Figure 2D). After the formation of pSi surface, two layers Once the basic device structure was created, the wafer was laser-diced into individual chips (37 chips / 4" Si wafer, Figure 1B).…”