Abstract
A body pressure relief system was newly developed with optical pressure sensors for pressure ulcer prevention. Unlike a conventional alternating pressure air mattress (APAM), this system automatically regulates air flow into a body supporting mattress with adaptive inflation (or deflation) duration in response to the pressure level in order to reduce skin stress due to prolonged high pressures. The system continuously quantifies the body pressure distribution using time-of-flight (ToF) optical sensors. The proposed pressure sensor, a ToF optical sensor in the air-filled cell, measures changes in surface height of mattress when pressed under body weight, thereby indirectly indicating the interface pressure. Non-contact measurement of optical sensor usually improves the durability and repeatability of the system. The pressure sensor was successfully identified the 4 different-predefined postures, and quantitatively measured the body pressure distribution of them. Duty cycle of switches in solenoid valves was adjusted to 0–50% for pressure relief, which shows that the interface pressure was lower than 32 mmHg for pressure ulcer prevention.
Highlights
Pressure ulcers are caused by a local breakdown of soft tissue due to prolonged high pressures at the interface of body and contact surface [1,2,3]
The ToF optical pressure sensors are placed on the internal bottom surface of the air-filled cells, which means that these sensors are physically non-contacted from the interface surface of the body
When the valve switch is ON with logic high, the valve is opened, and air is injected from the compressor to air-filled cell, thereby inflating the air-filled cell
Summary
Pressure ulcers are caused by a local breakdown of soft tissue due to prolonged high pressures at the interface of body and contact surface [1,2,3]. In order to relieve the interface pressure, manual repositioning of patients or support surfaces such as cushions has been required [1,2,3]. Air cells of APAMs sequentially inflate and deflate to relieve pressure for short periods. Commercial available APAMs have a passive control mechanism that repeats inflation and deflation into air cells, which occurs regardless of the pressed regions and pressure level. It is difficult to show even and lower pressure distributions against different stress regions across the body
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