Researchers at the University of Massachusetts Amherst have synthesized a new material that solves one of the most difficult problems in making wearable sensors: the pressure problem, according to a report by McMasters Consulting. Although wearable "electromechanical conversion" sensors are essential for improving health monitoring and off-site care applications, narrow detection range, inability to sense static/dynamic pressure simultaneously, and poor durability have limited their usefulness, the researchers said.

To address this issue, researchers have developed a full-fabric pressure sensor with high sensitivity to a wide range of pressures, from subtle heartbeats to body posture. This research has been published as "Humidity-Resistant, Broad-Range Pressure Sensors for Garment-Integrated Health, Motion, and Grip Strength Monitoring in Natural Environments," published in Advanced Materials Technologies.

Trisha L. Andrew, professor of chemical and chemical engineering at the University of Massachusetts Amherst, said, "Embedding such wearable sensors into comfortable clothing allows for continuous monitoring of a user's body movements and vital signs over a long period of time. Thus providing clinicians with granular data to remotely detect disease or physiological problems."

One way to obtain this information is to use miniature "electromechanical conversion" sensors that convert body movement into electrical signals (e.g., weak pulses that can be felt when a user places his or her hand on the chest). However, if there is too much movement, such as when the sensor wearer hugs or naps on his or her back, the added pressure can overwhelm the sensor and interrupt the data flow, so previous sensors have been unable to continuously monitor the body's natural activities.

To solve this problem, the researchers developed a wide-range sensor based on a material breakthrough that keeps the sensor working even during daily hugs, or even when leaning, sitting on it or squeezing. The secret, the researchers say, lies in the use of piezoelectric materials such as PEDOT-Cl (p-doped poly-3,4-ethylenedioxythiophene) for steam printing of clothing fabrics.

Using this solution, even the weakest body movements such as a heartbeat cause ions to redistribute throughout the sensor. That is, they can convert various mechanical movements of the body into electrical signals, which can then be monitored.

The researchers say that the sensor they have developed is the first fabric sensor capable of monitoring sensitive target populations in real time, for example, from workers under high stress in industrial environments to children and rehabilitation patients.

The unique advantage of the solution is that the all-fabric sensor can be embedded in comfortably worn, loose-fitting clothing, rather than being traditionally attached to the skin or embedded in tight-fitting garments, making it easier for the sensor to collect long-term data such as heart rate, breathing, joint movement, vocalization, step count and grip strength.