Liquid Metal-Based Multimodal Wearable Sensor Platform Enabled by Highly Accessible Microfabrication of PDMS with Tuned Mechanical Properties

The seamless integration of wearable devices into user-friendly and cost-effective healthcare systems requires constituent materials with high degrees of flexibility, stretchability, and adhesive properties without compromising performance during dynamic body movements. This study proposes a liquid metal (LM)-based multimodal skin-mountable sensor platform using polydimethylsiloxane tuned for enhanced stretchability and stickiness (sPDMS) to fully leverage the LM's deformability. A highly accessible end-to-end fabrication approach is proposed for multifunctional LM sensors from modeling to fabrication and packaging, all achieved without the need for cleanroom facilities or special equipment. The LM-based facile fabrication process tailored for sPDMS enables an adhesive-free sensor patch with microfluidic channels of 100 mu m width and stretchability up to 100%. A new analytical model provides enhanced estimation on the electromechanical behavior of LM channels compared with existing models. The funnel-assisted LM filling and tape-based channel sealing methods enable simple packaging of LM channels with robust external interconnection and direct skin-interfaced monitoring. The feasibility of this healthcare platform is demonstrated through a multimodal sensor patch with electromechanical and electrophysiological functionalities. The proposed technology addresses current challenges in the cost and complexity of microfabrication, expanding the boundaries of wearable devices for highly accessible and personalized healthcare devices. This study presents a highly accessible end-to-end fabrication approach for multifunctional skin-mounted liquid metal (LM) sensors. The method covers analytic modeling, MEMS-free simple microfabrication, funnel-assisted LM filling, and sealing for electrical interfaces. These sensors feature robust interconnections, high stretchability, and cost-effective production, expanding the accessibility of personalized healthcare devices. image