Skin-like micropumps transform human motion into fluidic flow via morphing valves

Abstract

Soft, skin-conformal fluidic systems are essential for wearable healthcare; however, micropumps that rely on rigid external hardware for actuation have limited portability and on-body integration. Here, we introduce OSMiPump, a power-free, strain-driven micropump that directly converts natural human motion into unidirectional fluid transport using a soft, monolithic architecture. OSMiPump integrates out-of-surface microchannels (OSMiCs) with self-actuated valves (OSMiValves), where cyclic tensile strain induces volume reduction and valve snap-through/snap-back, producing reliable directionality over repeated strain cycles. Computational fluid-structure interaction modeling and nonlinear shell deformation analysis validate the operating mechanism. Experimentally, OSMiPump exhibits predictable performance across valve geometries, strain levels and profiles, fluid viscosities, and inlet/outlet resistance configurations. At 20% strain, it achieves average flow rates up to ~0.16 µL/s under low-resistance conditions and maintains ~0.02 µL/s under high-resistance conditions, reaching peak pressures of ~11 kPa and sustaining an average pressure of ~0.6 kPa, with consistent operation over 100 cycles. The self-morphing architecture further enables tunable pumping behavior, including adjustable strain thresholds and response dynamics. Wearable demonstrations show direct actuation by body motion and enable both on-body delivery and removal for applications such as wound care and drug administration during physical rehabilitation, exercise, or daily activities. Integration into silicone socks and skin-mounted Tegaderm films illustrates the versatility of the platform. Together, these results establish OSMiPump as a soft, monolithic, and skin-conformal micropump for next-generation wearable biomedical systems.