ams revealed an ultra-thin sensor dedicated sensor for blood oxygen saturation (SpO2) measurement, bringing the capability to remotely monitor this vital sign to small consumer products such as earbuds, smart watches and wristbands, as well as to medical devices such as patches and oximeters.

The new AS7038RB SpO2 sensor enables innovative applications in remote diagnostic equipment, such as disposable patches used for SpO2 and electro-cardiogram (ECG) measurement in hospital emergency rooms.

In addition, ams also indicated that there are increasing evidence suggesting low SpO2 could be an early symptom of the COVID-19 disease before the onset of breathing difficulty in some at-risk patients. The development of a wearable SpO2 measurement device based on the AS7038RB can thus also be used for helping to treat people infected with the SARS-CoV-2 virus.

The sensor, housed in a package with a footprint of 3.70mm x 3.10mm and which is just 0.65mm thin, integrates a highly sensitive photodiode, four LED drivers, an analog front end, and a sequencer. It is supplied with application software for SpO2 and heart rate measurement. The analog front end also supports concurrent ECG measurement complying with the requirements of the IEC 6060-2-47 medical standard.

ams claims that the accuracy of the AS7038RB’s SpO2 measurements match closely with the outputs from medical-grade pulse oximeters used in hospital testing facilities. In addition, the filter enables the AS7038RB to capture optical signals in the 590nm-710nm and near infrared (800nm-1050nm) wavelength bands of interest for SpO2 measurement, while blocking interference from ambient light at other wavelengths.

When combined with ams’ high-sensitivity photodiode, which has a large light-sensitive area of 2.5mm2, this produces a very high optical signal-to-noise ratio. This eases implementation in optically challenging applications such as disposable chest patches, wristbands, and smart watches.

The sensor’s high sensitivity and high signal-to-noise ratio enable it to operate effectively with a low optical power output from the LEDs. The integrated LED drivers provide for adjustment of the drive current, so the OEM can balance system power consumption and measurement performance, helping to extend run-time between battery charges in devices such as earbuds, which contain a small battery power source.