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 via structural parameters (e.g., source electrode dimensions) and external excitation. Its miniaturized closed system enables wearable integration, eliminating external droplet dependency while simultaneously enabling biomechanical energy conversion (e.g., human motion) and monitoring physiological signals, which provides a potential strategy for the development of emerging wearable application devices.