PIN photodiode enhances bio sensor performance

The device provides increased photocurrent of 33µA in a 4.8mm by 2.5mm SMD package with a 5.4 mm2 sensitive area detecting visible and near infrared radiation.

Designed at a slim 0.48mm height, the device is idea for optical heart rate detection in wearable devices such as fitness trackers and smartwatches when placed between two pulsing green LEDs. They are also used in SpO2 measurement in medical monitors when combined with red and infrared emitters. 

The new Vishay VEMD8081 offers 15 % greater reverse light current than its predecessor, the Vishay VEMD8080, while maintaining the same package dimensions.

It utilises Vishay’s proven wafer technology to detect visible and near infrared radiation.

The device is a drop-in replacement that can improve performance by increasing signal output, or extend battery life by reducing LED current. 

The rectangular shape maximises the area of the photodiode receiving reflected light, eliminating the wasted area typically found in square photodiodes.

For heart rate measurement in wearable devices, the light reflected off the skin is received by the photodiode and converted to an output current, with the device’s increased sensitivity enabling more accurate measurements.

Other features include a wide spectral range from 350 nm to 1100 nm and fast switching times and low capacitance of 50 pF enable high sampling rates.

The device has ± 65° angle of half-sensitivity with a temperature range of -40 °C to +85 °C and it offers 840nm wavelength of peak sensitivity.

It is RoHS-compliant, halogen-free, and Vishay Green.

Moisture sensitivity level (MSL) of 3 is in accordance with J-STD-020 for a floor life of 168 hours

Applications cover high speed photo detector and wearables

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