The reference design integrates hardware and software to implement blood pressure measurement, heart-rate measurement (HRM), heart rate variability (HRV) and electrocardiograms (ECG). The AS7024 includes three LEDs, photodiodes, an optical front end and sequencer for HRM, and an analog front end for ECG in a 6.1mm by 2.7mm package.
The reference design also enables calculated measurements of vagal tone and arterial elasticity, as well as skin temperature and skin resistivity via interfaces to external sensors.The AS7024 can be included in fitness bands, smart watches and patches.
The blood pressure is derived by synchronized measurement of the heart rate by the photoplethysmography (PPG) method and electrocardiography. The accuracy of the AS7024’s blood pressure measurements has been established in a clinical trial carried out at the Medical University of Graz in Austria, according to IEEE standard for cuffless wearable devices.
However, it is expected that medical equipment based on that chip would need to be subjected to medical regulatory approval. As such the chip may find easier design wins in “life-style” and “well-being” products such as fitness bands and smart watches.
It is notable that Leman Micro Devices SA, developer of the V-sensor is putting its chip through clinical trials prior to submission to the US Food and Drug Administration and other authorities globally for certification of medical accuracy (see Vital signs sensor could transform smartphones).
The AS7024 vital signs sensor is in production with pricing below $2.00. The reference design and evaluation board for the AS7024 is available on request. It includes a Simblee Bluetooth wireless module for connectivity, wireless charging capability and a smartphone app which displays measurements of heart rate, blood pressure, vagal tone and arterial elasticity.