Flexible skin patch analyses sweat in real-time

March 02, 2017 // By Julien Happich
Researchers from UC Berkeley have devised a flexible sensor system that can measure metabolites and electrolytes in sweat, calibrate the data based upon skin temperature and sync the results in real time to a smartphone.

Reporting their findings in the journal Nature with a paper titled "Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis", the researchers describe plastic-based sensors able to simultaneously and selectively measures sweat metabolites (such as glucose and lactate) and electrolytes (such as sodium and potassium ions), as well as the skin temperature to calibrate the response of the sensors, interfaced with a small wearable board-based processing unit. The small board performs signal transduction, conditioning, processing and can then wirelessly transmit the results to a smartphone.

This non-invasive monitoring of multiple biochemicals in sweat in real-time could alert users to health problems such as fatigue, dehydration and dangerously high body temperatures.

The flattened sensor system, showing the sensor
array (red dashed box) and the different signal
conditioning ICs (white dashed boxes) on the
flexible PCB.

The self-sufficient sensor system was made into a wristband and the researchers expect it could be used to measure the detailed sweat profile of human subjects engaged in prolonged indoor and outdoor physical activities, to make a real-time assessment of the physiological state of the wearer.

Schematic of the sensor array for multiplexed
perspiration analysis

The prototype processing board was built from many off-the-shelf components to condition the various sensor signals, but these functions could be further integrated into an ASIC, while the number of biochemical being monitored could also be ramped up.