Microfluidic-based redesign of a humidity-driven energy harvester†

Integrating microfluidic elements onto a single chip offers many advantages, including miniaturization, portability, and multifunctionality, making such systems highly useful for biomedical, healthcare, and sensing applications. However, these chips need redesigning for compatibility with microfluidic fabrication methods such as photolithography. To address this, we integrated microfluidics technology into our previously developed humidity-driven energy harvester to create a self-powered system and redesigned it so that it could be fabricated using photolithography and printing. The device comprises stacked electrodes, cation-exchange membranes, and microchannels. The multi-element version of the device generated ten times more voltage than the single-element version. Both versions produced stable patterns of voltage output with respect to the fluctuations in humidity in both controlled and real-world environments. Their potential as humidity sensors is supported by the correlations exhibited between humidity and voltage output. The capacity of the device to respond to changes in perspiration-induced changes in humidity suggests its usefulness as a power source for wearable sensors. This novel device element, which can be easily integrated into other microfluidic devices, is expected to provide a new approach to powering microfluidic-based wearable sensors.