Wireless Smart Devices Monitor Health by Detecting Sounds

Health or Disease? Listen Up!

Auscultation is an integral part of almost every patient encounter with a doctor. The sounds emitted by the body provide crucial information about the quality of breathing, heart activity, or gastrointestinal function. In a new study published in the journal Nature Medicine, a team led by Professor John A. Rogers introduced new miniaturized wearables that, when applied to the patient's skin, continuously monitor subtle body sounds.

Much More than a Wireless Stethoscope

The device is housed in soft silicone measuring 40 × 20 × 8 mm (see figure). Inside there are two high-performance digital microphones (one facing toward the body's surface and the other outward), an accelerometer, a battery, and electronics for wireless data transmission. Because the device detects sound in two different directions, a special algorithm can distinguish sounds generated by the observed organ from ambient noise.

Fig.  A wireless network of miniaturized sensors applied to the skin for detecting bodily movements and sounds, enabling continuous monitoring of physiological functions

How to Map a Single Breath?

The testing involved 35 adults with chronic lung disease and 20 healthy controls, with a total of 13 devices applied to the front and back of their chests, allowing for real-time spatiotemporal mapping of breathing (device response time is approx. 0.2 ms). Patterns of movement and sounds made by healthy lungs were identified and compared with data from patients after partial lung resections or with pulmonary fibrosis and other diseases. Continuous lung function monitoring has great potential for applications such as monitoring patients immediately after lung surgery or those on mechanical lung ventilation, where ventilator settings could be adjusted in real-time based on the patient's condition.

Thoracic surgeon Dr. Ankit Bharat, who led the clinical testing of wearables in adult patients, sees their main advantage as the ability to simultaneously listen to and compare different lung areas. He humorously says that the tested devices work like “up to 13 very experienced doctors who separately examine different areas of a patient's lungs with stethoscopes and collectively, with their synchronized minds, create a video from the continuous dynamic evaluation of lung health on a computer screen.”

Fragile Lungs of Infants

The second group for which these devices were developed comprises prematurely born infants. Some of these babies are smaller than commonly used stethoscopes, making their monitoring technically challenging. The wireless devices enable non-invasive continuous monitoring during waking and sleeping that does not disturb the infants.

One of the main issues for infants with underdeveloped lungs is apnea, a complication that most commonly leads to extended hospitalization or death. The device was tested in neonatal intensive care units on 15 infants with respiratory or intestinal motility disorders. When applied to the suprasternal notch, it was capable of detecting apnea and classifying whether it was caused by airway obstruction.

Monitoring Intestinal Motility

Part of the device testing on premature infants involved monitoring gastrointestinal processes using four wearables placed on the abdomen. Initial results corresponded to data obtained from adults using traditional probes typically used for monitoring. A reduction in sounds associated with bowel movements could serve as an early warning sign of impending gastrointestinal complications, such as dysmotility, obstruction, or necrotizing enterocolitis.

Conclusion

The study introduced technology suitable for continuous monitoring of body sounds and movements, which can be used as a reliable source of physiological signals in both home and hospital environments. The authors suggest exploring future uses of these technologies for monitoring swallowing and respiration in patients with dysphagia, monitoring speech patterns in patients with dementia, or tracking cardiorespiratory functions in patients with diabetes, hypertension, cardiac arrhythmias, asthma, or anxiety and depression.

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Sources:
1. Yoo J. Y., Oh S., Shalish W. et al. Wireless broadband acousto-mechanical sensing system for continuous physiological monitoring. Nat Med 2023 Dec; 29 (12): 3137–3148, doi: 10.1038/s41591-023-02637-5.
2. Morris A. First-of-their-kind wearables capture body sounds to continuously monitor health. Northwestern University, 2023 Nov. 16. Available at: https://news.northwestern.edu/stories/2023/11/first-of-their-kind-wearables-capture-body-sounds-to-continuously-monitor-health