Microchannel-confined droplet-based electricity generator for biomechanical energy conversion and sensing

Triboelectric nanogenerators (TENGs) are positioned as a critical sustainable power solution for harvesting low-frequency mechanical energy or sensing. Although solid-solid contact-based TENGs can provide sustainable power to diminish external battery reliance and enhance portability and operational longevity, suboptimal energy output at low-frequency excitation, irreversible material damage under long-term operation and inadequate energy supply remain a challenge. Solid-liquid contact-based TENGs present an alternative approach, but rigid and bulky configurations hinder their integration toward wearable devices and the development of real applications. To address these challenges, we propose a flexible microchannel-confined droplet-based electricity generator (MC-DEG). By enclosing droplet chains in a flexible microfluidic channel and employing a dual-drain electrode structure (inspired by transistor design), the device achieves dual-peak electrical output that efficiently releases electrostatic induction charge accumulation during liquid reciprocation. This design enhances charge collection efficiency by >75% compared to single-electrode systems. The MC-DEG's output is tunable <i>via</i> structural parameters (<i>e.g.</i>, source electrode dimensions) and external excitation. Its miniaturized closed system enables wearable integration, eliminating external droplet dependency while simultaneously enabling biomechanical energy conversion (<i>e.g.</i>, human motion) and monitoring physiological signals, which provides a potential strategy for the development of emerging wearable application devices.