Biosensor innovation delivers 24/7 heart rate measurement for wearables
The AS7000 solution incorporates a highly integrated optical sensor module accompanied by software backed by opto-mechanical design-in support from ams.
Housed in a compact 6.1 mm x 4.1 mm x 1.0 mm package, the AS7000 is the industry’s first complete integrated health and fitness solution wearables intended to be worn constantly, at rest and when exercising. The introduction of the module raises the prospect of fitness bands as well as sports and smart watches allowing for accelerated design cycles and replacing the cumbersome, uncomfortable electro-cardiogram (ECG) chest strap in lifestyle, fitness and health monitoring applications.
The ams solution contains the AS7000 module including the LEDs, photo-sensor, analog front end (AFE) and controller as well as application software required to implement an accurate optical HRM/HRV fitness band product. In addition to HRM/HRV, the module also enables skin temperature and skin resistivity measurements by providing interfaces to external sensors.
Drawing on its expertise in optical sensing in mobile devices, ams provides OEMs with electrical, mechanical and optical design guidelines to enable them to quickly realize a successful implementation. These guidelines address critical opto-mechanical challenges such as the design and material of the wrist strap and housing, and specific optical design considerations such as the air gap and glass thickness.
The operation of the AS7000 is based on photoplethysmography (PPG), an HRM method which measures the pulse rate by sampling light modulated by the blood vessels, which expand and contract as blood pulses through them. Unlike existing optical AFEs, which produce raw PPG readings, the AS7000 integrates a digital processor which implements algorithms developed by ams which convert the PPG readings into digital HRM and HRV values.
When the AS7000 is paired with an external accelerometer, these algorithms also filter out motion artifacts attributable to the beating of the heart which interfere with PPG readings. Combined with the low noise and high sensitivity of the AS7000’s analog circuitry, this means that the module can maintain high accuracy whether the user is resting or exercising.
The AS7000’s low-power design is well suited to applications in fitness bands, smart watches, sports watches, and devices in which board space is limited and in which users look for extended, multi-day intervals between battery recharges.
A complete HRM/HRV wristband demonstration kit is available on request from ams. Containing a fitness band-mounted AS7000, it uploads its HRM and HRV readings via a Bluetooth® interface board to any smartphone or tablet running the Android™ operating environment. An ams-developed heart rate app presents HRM and HRV readings and allows for real time logging of all the data.
The AS7000 is available for sampling now. Unit pricing is $6.00 in order quantities of 1,000.
A demonstration kit for the AS7000 is available.
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