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Biomaterials

Biomaterials - Poster Session E

Poster N16 - Fabric Pressure Sensor for Management of Pressure Ulcers

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Pressure (decubitus) ulcers result from prolonged pressure on the skin, typically affecting bony areas like the tailbone and heels, especially in immobilized/low mobility patients. These ulcers diminish the quality of life and may contribute to infections and mortality among patients. Annually, over 2.5 million Americans develop pressure ulcers, with substantial economic implications, costing up to $11 billion in treatment expenses nationwide. Hospital understaffing exacerbates the issue, as manual patient rolling, the primary prevention method, becomes challenging. To overcome these challenges, we propose a solution: a capacitive pressure sensor array to continuously monitor and detect pressure levels on the skin in real-time without human intervention. This sensor can be integrated into hospital bedding and has the potential to be programmed to alert caregivers when there is prolonged pressure on the skin, which may begin to form a pressure ulcer. Our design aims to enhance patient quality of life while reducing medical costs and addressing the current understaffing crisis across hospitals.

Materials and

Methods:  Capacitive pressure sensors function as parallel plate capacitors with a dielectric sheet between two flexible electrodes. The design for the capacitive sensor array, based on a paper by Gummus et al., utilizes two layers of conductive silver-plated knit fabric as flexible electrodes, two layers of thermoplastic polyurethane (TPU) as dielectric layers, heat-activated tape to fuse the layers, and a 4 mm thick sheet of plexiglass to act as the pressure plate [1]. Fusion360 models were used to laser cut the conductive fabric, heat-activated tape, and plexiglass. Using a heat press, 2 3x3 pressure pads, and 1 2x10 pressure pad were fabricated. The pressure pad air pockets measured 5mm x 5mm and were distributed 5mm apart. The pressure pads are then connected to an MPR121 Capacitive Touch sensor, via alligator clips, which is then connected to an Arduino. A preliminary code was written to obtain relative capacitance readings. The sensors operate by altering capacitance when pressure is applied, converting these readings into electrical signals, and then into pressure readings.

Results, Conclusions, and Discussions: The final prototype can read real-time relative capacitive readings from more than 1 pressure pad when connected to an MPR121 capacitive touch sensor. The more weight applied to a pressure pad, the lower the relative capacitance reading compared to untouched pads. This is demonstrated in Figure 1B, when a 10 lb. weight is placed on top of a pressure pad, the sensor reads a relative capacitance of 165 whereas when a 3 lb weight is applied, the pressure pad reads a relative capacitance of 198.

As seen in Figure 1C, the final design can accommodate a maximum of 12 fully functional pressure sensor arrays connected to a touch sensor and integrated into bedding or seating. This design enables continuous, real-time monitoring of external pressure on a patient’s skin, prioritizing usability and serviceability while adhering to medical industry standards. The sensors measure relative capacitance and can be sealed under bedding to prevent moisture or contamination. Integrated with Neuro20’s electrical muscle stimulation (EMS) technology, the sensors can stimulate blood flow when detecting high pressure, preventing decubitus ulcer formation.

The schematic demonstrates multiple pressure pads throughout a bedsheet to continuously monitor high-risk areas. Integration with Neuro20’s EMS technology is also illustrated. Accurate pressure readings from relative capacitance require baseline measurements and a calibration curve, developed through human testing. Machine learning implementation with human testing could establish a robust baseline for external pressure, enhancing sensor array effectiveness.

The final design addresses public health and safety by preventing pressure ulcers, reducing patient suffering and healthcare costs. It mitigates healthcare understaffing issues by continuously monitoring and relieving pressure without requiring nurse intervention. By preventing pressure ulcers, the design alleviates financial burdens on hospitals and patients, as pressure ulcers are preventable and costly to treat. Overall, the final design promotes patient comfort, improves healthcare outcomes, and reduces the need for pressure ulcer treatments, considering various global factors.

Acknowledgements (Optional):  This research is supported by the National Science Foundation (NSF;CBET#2238173). Regards to Neuro20 for support on the project.