Accelerometer Contact Microphone (ACM) Sensor Offers the Best of Both for Future Medical Monitoring
The hermetically sealed sensor can track everything from body motion to lung sounds by combining accelerometer and microphone functions.
A team of researchers at the Georgia Tech have detailed a new sensor for healthcare tasks, which uses microelectromechanical systems (MEMS) technology to combine the functions of an accelerometer and a contact microphone to monitor everything from bodily movements to lung sounds.
"Mechano-acoustic signals emanating from the heart and lungs contain valuable information about the cardiopulmonary system. Unobtrusive wearable sensors capable of monitoring these signals longitudinally can detect early pathological signatures and titrate care accordingly," the team explains of the project's goal. "Here, we present a wearable, hermetically-sealed high-precision vibration sensor that combines the characteristics of an accelerometer and a contact microphone to acquire wideband mechano-acoustic physiological signals, and enable simultaneous monitoring of multiple health factors associated with the cardiopulmonary system including heart and respiratory rate, heart sounds, lung sounds, and body motion and position of an individual."
"The encapsulated accelerometer contact microphone (ACM) utilizes nano-gap transducers to achieve extraordinary sensitivity in a wide bandwidth (DC-12 kHz) with high dynamic range. The sensors were used to obtain health factors of six control subjects with varying body mass index, and their feasibility in detection of weak mechano-acoustic signals such as pathological heart sounds and shallow breathing patterns is evaluated on patients with pre-existing conditions."
"Right now, medicine looks to EKGs for information on the heart, but EKGs only measure electrical impulses," Professor Farrokh Ayazi told Electronic Design, which brought the project to our attention, in an interview. "The heart is a mechanical system with muscles pumping and valves opening and shutting, and it sends out a signature of sounds and motions, which an EKG does not detect. EKGs also say nothing about lung function."
The ACM itself is just 2mm² (around 0.08in²), and is produced in a two-layer design separated by a 270nm gap. After being hermetically sealed inside a vacuum cavity, the resulting sensor is high-bandwidth with low signal noise — and, the researchers found, more than capable of disregarding external noises from outside the body.
The team's work has been published in the journal Digital Medicine under open-access terms.