Google Pursues Multiple Paths to Blood Pressure Measurement

Google is exploring new ways to measure blood pressure using wearable devices, according to a recently published patent. The company's latest idea involves placing miniature electrodes underneath a fingertip to send an electrical signal through the tissue and track changes in blood flow.

The patent describes a miniaturized impedance plethysmography sensor (IPG sensor) that can be built into various computing devices, including smartwatches. The system uses four electrodes: two to send an excitation signal and two to measure the resulting electrical response. By tracking changes in blood flow, the device can produce a pulsatile waveform that reflects the blood pulse and estimate blood pressure.

This is not Google's first foray into blood pressure measurement. A separate patent published last month describes a finger cuff containing an inflatable bladder, multiple pressure sensors, and optical sensors. The system would inflate around the finger while an array of barometric sensors maps pressure around the digital artery.