Silicon PIN photodiode improves sensitivity in biomedical applications

Vishay Intertechnology, Inc. has released a new silicon PIN photodiode that brings a higher level of visible/near-infrared wavelength sensitivity to biomedical applications such as heart rate and blood oxygen monitoring. The new VEMD8082 features increased reverse light current, decreased diode capacitance, and faster rise and fall times compared to previous-generation solutions. Also, its small form factor of 4.8mm x 2.5mm x 0.5mm makes it suitable for integration into low-profile devices such as smartwatches.

The high sensitivity provided by the device is particularly important in biomedical applications such as photoplethysmography (PPG), where the photodiode detects changes in blood volume and flow by measuring the amount of light absorbed or reflected by blood vessels. In such applications, precise measurements are vital for diagnosing and monitoring conditions such as cardiovascular disease.

Specifications for the new device contributing to its high sensitivity compared to previous-generation devices incorporate a radiant sensitive area of 6mm² and an increase in reverse light current of 18% to 20%, depending on wavelength. Decreased diode capacitance from 50pF to 46pF and faster rise times of 40ns vs. 110ns allow for higher sampling rates.