Sensor Reference Design Enables Healthcare Wearables

Sensor-solutions company ams introduces the first integrated vital sign sensor reference design based on its AS7024.The solution can perform accurate, fast, and convenient 24/7 cuffless blood pressure measurement. The reference design integrates all the hardware components, including the AS7024, as well as the software required to implement blood pressure measurement, heart-rate measurement (HRM), heart rate variability (HRV) and electrocardiograms (ECG).


The AS7024 sensor IC includes three LEDs, photodiodes, an optical front end and sequencer for HRM, and an analog front end for ECG in a low-profile 6.1mm x 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.


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The AS7024's small form factor is particularly well suited for fitness bands, smart watches, sports watches and smart patches, in which board space is limited. It also opens the door for vital sign monitoring to a wider range of form factors and end markets such as automotive or personal health monitoring.


HRM operation is based on photoplethysmography (PPG), a technique that measures the pulse rate by sampling light modulated by the blood vessels, which expand and contract as blood pulses through them. Electrocardiography is a standard method for measuring the electrical pulses generated by the sinoatrial node of the heart.


Proprietary software in the AS7024 reference design, which was developed in collaboration with a partner, analyzes synchronized HRM and ECG measurements to calculate blood pressure. The accuracy of the AS7024's blood pressure measurements has been validated in a clinical trial carried out at the Medical University of Graz in Austria, according to IEEE standard for cuffless wearable devices.


The results produced by the reference design were compared to a reference measurement taken with surgical-grade cuffed blood pressure measurement equipment. Across a total of more than 1,000 measurements on more than 100 subjects between 18 and 65 years of age, the AS7024 reference design was proven to be accurate to <± 7.5 mmHg for systolic pressure and to <± 5.5 mmHg for diastolic pressure.


The AS7024 vital signs sensor is available now in production volumes. Unit pricing is <$2 each/1,000,000 for the sensor frontend IC.  For further enlightenment, checkout the product brief and request a datasheet while you’re at it.

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