Light-sensitive photodiode improves bio sensors for slim wearables

Featuring an increased photocurrent of 33 microA, the VEMD8081 is a high speed, silicon, PIN photocurrent from Vishay Intertechnology. It enables improved bio sensor performance for wearable devices.

The VEMD8081 is supplied in a 2.5mm surface mount package and has a low profile of 0.48mm.

The addition to Vishay’s optoelectronics portfolio, has enhanced sensitivity to visible and infrared (IR) light. The 4.8 x 2.5mm package offers increased typical reverse light current of 33 microA for improved bio sensor performance in wearable devices and medical applications.

The VEMD8081 offers 15 per cent greater reverse light current than its predecessor, the VEMD8080, while maintaining the same package dimensions. It is a drop-in replacement that can improve performance by increasing signal output, or extend battery life by reducing LED current.

For heart rate measurement in wearable devices, such as fitness trackers and smart watches, the VEMD8081 is placed between two pulsing green LEDs. The light reflected off the skin is received by the photodiode and converted to an output current for measurements. The VEMD8081’s rectangular shape maximiaes the area of the photodiode receiving reflected light, eliminating the wasted area typically found in square photodiodes. When combined with red and IR emitters, the photocurrent is suitable for SpO2 measurement in medical monitors.

The high sensitivity and radiant-sensitive area measuring 5.4mm² uses Vishay’s proven wafer technology to detect visible and near IR radiation over a wide spectral range from 350 to 1100nm. For high sampling rates, the device offers fast switching times and low capacitance of 50pF.

The VEMD8081 features a ± 65 degree angle of half-sensitivity, operating temperature range of -40 to +85 degrees C, and 840nm wavelength of peak sensitivity. The RoHS-compliant, halogen-free photodiode provides a moisture sensitivity level (MSL) of 3 in accordance with J-STD-020 for a floor life of 168 hours.

Samples and production quantities of the VEMD8081 are available now, with lead times of 10 weeks.

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