A reusable microfluidic sweat collection system leveraging a magneto-active bistable microvalve

We develop a reusable sweat collection device that leverages a magneto-active bistable microvalve to enable accurate body composition analysis without interference between measurements. Traditional sweat sensors often suffer from data inaccuracies due to the mixing of old and new samples. Our device addresses this issue by using multiple chambers to separate samples, with the microvalve controlling the flow to prevent data overlap. The magneto-active valve responds to a smartphone's magnetic field, allowing for remote control for its opening or closing. The valve is constructed from a bistable shell structure incorporating NdFeB powder blended with elastomer, ensuring that its cracking pressure prevents unintended activation from sweat pressure. The valve maintains its state without requiring continuous external input once set. Additionally, we introduce dimples in the microfluidic channel to enhance sealing. This reusable sweat collection device operates without the need for a continuous power supply, advancing the miniaturization and reusability of non-invasive body fluid monitoring systems. Potential applications include drug delivery systems, space environment monitoring, and soft robotics, where precise microfluidic flow control is essential.