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 that 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.

Self-powered ultrasensitive and highly stretchable temperature–strain sensing composite yarns

“…For example, strain sensors with either high gauge factor (GF) (up to 1000-16 000) and low strain at break (2-7%) 19,20 or, vice versa, with a wide range of working strain (up to 280-300%) but low GF (0.06-13.1), have been reported. [21][22][23] Recently, this challenge has been partially addressed by incorporating auxetic mechanical metamaterials (GF B 800 and strain-at-break of 160%), 24 or by patterning silver nanowires on polydimethylsiloxane films (GF B 150 000 and strain-at-break of 60%). 25 Beyond the sensitivity/deformation dichotomy, the need for (typically rigid) energy storage devices is another critical constraint limiting the practical use of flexible and highly deformable sensors.…”

Disposable silicon-based all-in-one micro-qPCR for rapid on-site detection of pathogens

“…2b, c ). Without this step, the metal films electroplated do not adhere to the surface of the substrate 24 . The pSi layer also allows thermal bonding of sheets of polymer films in an ordinary heat press after patterning through laser-cutting (Fig.…”

“…First, each wafer is plated electrolessly for 20 s (in 80 µM KAuCl 4 and 0.5% HF) to form a thin layer of gold particulate film. The wafer is then placed inside an etching bath containing an aqueous solution of H 2 O 2 and HF with a ratio of 1:20 v/v (30% H 2 O 2 : 10% HF) to perform metal-assisted chemical etching (MACE) of Si for 10 min [22][23][24] . This process forms a 500 nm thick nanoporous Silicon (pSi) layer on each side of the wafer (Fig.…”

PEDOT:PSS-Modified Cotton Conductive Thread for Mass Manufacturing of Textile-Based Electrical Wearable Sensors by Computerized Embroidery

“…[41][42][43][44][45][46] Furthermore, the electrical resistance of the embroidered patterns can be reduced by denser stitching, using a longer stich length or deposition of additional materials by electroplating. [43,[47][48][49] (ii) In comparison to metalcoated conductive threads, the electrical resistance of PECOTEX were a few orders magnitude higher; however, the electrical resistance of the metallic threads increased and became comparable to the PECOTEX after embroidery. (iii) Although we did not study in detail, we did notice a drop in electrical conductivity of the patterns embroidered with PECOTEX over time.…”