Light plays a growing role in wearable Health Tech devices. By measuring light reflected by different tissues and materials, wearables can measure heartbeats and blood pressure; companies are developing systems that can even measure blood glucose and other important biometrics. There’s one problem with these systems, however. The light sensors consume a significant portion of the device’s overall power budget.
ActLight is a company in Switzerland has developed a new approach to optical sensing for wearables, in co-operation with the École Polytechnique Fédérale de Lausanne (EPFL). Most systems use a photodiode to measure the amount of light received. Changes in those levels are used to identify target actions, such as a heartbeat. The problem is that this approach requires a high voltage source of electricity, which consumes power. The ActLight approach is very different; using a low-voltage source, the chip watches for changes in light levels, rather than constantly measuring their levels. The result is a small power savings with every heartbeat, which can add up to an 80% reduction of overall power consumption while still delivering the same information.
The company hopes to license their technology to wearables manufacturers. The system is so small that it can be integrated onto a chip that performs other functions, which can lower costs and reduce device size. The technology is ready for full-scale production, so we may see smartwatches and other heart rate monitoring devices last much longer between charges starting in a year or two.