The sensor combined a radar with signal analysis algorithms to measure how the body moves as the heart beats. Since, body movements vary considerably, the software filters isolate just the heart's minute motions.
"Measuring respiration and heart rate – without attaching cumbersome wires to the body – will greatly benefit modern medicine and home healthcare," explains Toru Sato, lead researcher and Kyoto University professor of communications and computer engineering.
"Moreover, it will reduce stress by not subjecting the individual to a feeling of being monitored."
The original technology showed promise but the prototype was the size of a microwave oven. To improve prospects for implementation, the group shifted their focus toward refining the device.
"After extensive testing we achieved great improvements," continues Sato. "The device now utilizes the 79 GHz frequency band, instead of the previous 60 GHz. We also incorporated CMOS semiconductors. As a result, range and resolution improved, and it's now only about one tenth the size – as big as a smoke detector."