TNO at Holst Centre Develops Smart Sensor Mat

TNO at Holst Centre has developed an ultrathin conformable smart sensor mat that can detect a person’s breathing rate, heart rate and posture. The multi-modal sensing mat consists of a combination of printed piezo-resistive and piezo-electric sensors.

In one implementation, the mat can be placed under a bed sheet, enabling long-term monitoring of patients in a hospital bed or babies sleeping at home. The mat can also be integrated into the seat and back of an office chair, increasing and extending the vitality of our work force.

When used in a car seat, the mat can monitor posture and driver alertness. TNO at Holst Centre continues to develop the sensor mat to include monitoring of additional vital signs.

Approximately 26% of people between the ages of 30 and 70 suffer from sleep apnea worldwide. People with sleep apnea are four times more likely to have a stroke and many die each year from cardiovascular diseases caused by this condition. As the healthcare costs involved are increasing rapidly across the globe, the demand for a cure is on the rise.

People suffering from sleep apnea are often monitored in so-called sleeping centers, having to sleep there several nights under less-than-ideal circumstances. Peter Zalar, Program Manager Large-Area Sensors at TNO at Holst Centre, explains: “

“The posture, breathing rate, and heart rate of a person laying on a bed can be ascertained using a large-area matrix of piezo-electric and piezo-resistive force sensors,” said Peter Zalar, program manager large-area sensors at TNO at Holst Centre. “Because these sensors are printed on a thin elastomer, they are very sensitive, quickly picking up a signal again even if the patient has moved. This maximizes data quality, enabling patient monitoring to be performed completely remotely and reliably. Since the sensors are unobtrusive and do not cause discomfort, the patient does not notice the device – allowing for the accumulation of vast amounts of unbiased data. Furthermore, by combining multiple data sources, the state of the patient’s health can be determined with greater certainty.”

The smart sensor mat enables long-term monitoring, as it is a non-intrusive device. There are many possible applications to use the sensor mat, for example in a baby bed to monitor an infant’s activity and breathing rate.

“Another field of application is in cars,” said Zalar. “When used in a car seat, the mat can monitor sitting posture and heart rate and give an indication of the driver’s alertness level. Even with the advent of autonomous driving technologies, the driver formally still needs to pay attention, but the chance of being distracted or dosing off increases due to driver inactivity. The mat could prevent people from falling asleep behind the steering wheel, which could help save lives.

“When integrated in an office chair, the mat can signal when it is necessary to change position or even to get up and get some exercise,” added Zalar. “This helps increase and extend the vitality of our work force. Additionally, it could help designers of office furniture to create more ergonomic chairs by identifying areas of a chair which can cause discomfort or harm to a person.”

The number and ratio of piezo-electric and piezo-resistive sensors within the matrix structure can be adjusted. This makes the mat highly cost effective in the long term, as more or fewer of either sensor type can be used on a larger or smaller surface.