Engineering molecular bridges for fabricating cross-linked LM-HPDMS highly sensitive capacitive sensors for wearable monitoring

Flexible capacitive sensors hold great promise for deployment in electronic skin, display touchscreens, and intelligent robotics due to their conformability and lightweight characteristics. However, a significant challenge is the low dielectric constant of polymers, which results in diminished sensitivity. In this study, a capacitive sensor with high liquid metal (LM) content (60 % LM volume fraction) was developed by self-assembling a γ- Mercaptopropyl triethoxysilane (KH580) silane coupling agent onto the LM surface via electrostatic interactions, followed by successful cross-linking with hydroxyl-terminated polydimethylsiloxane (HPDMS). This approach notably enhanced the sensitivity factor to 0.889 kPa⁻¹ and demonstrated excellent cycling performance, maintaining a 100 % response level after 10,000 test cycles. The flexible capacitive sensor reliably monitors subtle changes in motion, sound, and pulse in real-time with stability. It can also detect the grasping of objects of various sizes and monitor temperature changes.