This tiny electronic device applied to the skin can pick up heart and speech sounds

November 18, 2016

Illustration of the assembled acoustic sensor device and its interface with soft electrophysiology measurement electrodes and flexible cable for power supply and data acquisition (credit: Yuhao Liu et al./Science Advances)

Researchers from the University of Colorado Boulder and Northwestern University have developed a tiny, soft, wearable acoustic sensor that measures vibrations in the human body and can be used to monitor human heart health and recognize spoken words.

The stretchable Band-aid-like device attaches to the skin on nearly any surface of the body, using “epidermal electronics” to capture sound signals from the body.

It’s a sort of tiny, wearable stethoscope. As described in an open-access paper published Nov. 16 in Science Advances, a sister journal of Science, it can detect things like heart murmurs in cardiac patients and lung problems, and can monitor ventricular assist devices. It can also be used to pick up speech sounds (for automated speech recognition or controlling video games and other machines), and even movements in gastrointestinal tracts.

Listening in on the body

The sensor can also integrate electrodes that can record electrocardiogram (ECG) signals that measure the electrical activity of the heart as well electromyogram (EMG) signals that measure the electrical activity of muscles at rest and during contraction.

While the sensor was wired to an external data acquisition system for the tests, it can easily be converted into a wireless device, said CU Boulder Assistant Professor Jae-Woong Jeong, a lead author. Such sensors could be of use in remote, noisy places — including battlefields — producing quiet, high-quality cardiology or speech signals that can be read in real time at distant medical facilities.

Using the data from these sensors, a doctor at a hospital far away from a patient would be able to make a fast, accurate diagnosis, said Jeong.

Process loop for a speech-based human-machine interface (credit: Yuhao Liu et al./Science Advances)

Vocal cord vibration signals also could be used by the military personnel or civilians to control robots, vehicles or drones. The speech recognition capabilities of the sensor also have implications for improving communication for people suffering from speech impairments, he said.

As part of the study, the team used the device to measure cardiac acoustic responses and ECG activity — including the detection of heart murmurs — in a group of elderly volunteers.

The researchers also were able to detect the acoustical signals of blood clots in a related lab experiment, said Jeong.

University of Colorado Boulder | CU Science Story — Wearable Tech

Abstract of Epidermal mechano-acoustic sensing electronics for cardiovascular diagnostics and human-machine interfaces

Physiological mechano-acoustic signals, often with frequencies and intensities that are beyond those associated with the audible range, provide information of great clinical utility. Stethoscopes and digital accelerometers in conventional packages can capture some relevant data, but neither is suitable for use in a continuous, wearable mode, and both have shortcomings associated with mechanical transduction of signals through the skin. We report a soft, conformal class of device configured specifically for mechano-acoustic recording from the skin, capable of being used on nearly any part of the body, in forms that maximize detectable signals and allow for multimodal operation, such as electrophysiological recording. Experimental and computational studies highlight the key roles of low effective modulus and low areal mass density for effective operation in this type of measurement mode on the skin. Demonstrations involving seismocardiography and heart murmur detection in a series of cardiac patients illustrate utility in advanced clinical diagnostics. Monitoring of pump thrombosis in ventricular assist devices provides an example in characterization of mechanical implants. Speech recognition and human-machine interfaces represent additional demonstrated applications. These and other possibilities suggest broad-ranging uses for soft, skin-integrated digital technologies that can capture human body acoustics.