Abstract
Diabetic Foot Ulceration (DFU) is a common complication of diabetes mellitus and accounts for a disproportionately large number of lower limb amputations. Mortality following major amputation is exceptionally high. In the US, diabetic treatment annual costs are estimated at USD 245 billion, with 33% associated with DFU. The average cost for DFU in US estimated to be USD 13,179 per episode with incremental severity and USD 38,077 per amputation, the financial impact of DFU is hefty even before indirect cost like loss of productivity is included. DFU is caused by the combination of peripheral neuropathy, foot deformity and trauma. With loss of protective sensation in their feet, patients are unable to prevent trauma and detect early tissue damage that eventually leads to DFU. The primary prevention and detection method for DFU is regular physician inspections, but frequent visits to clinics incur high cost while straining healthcare resources unnecessarily. Daily self-inspection is the most cost-effective solution yet patient compliance is typically low. Therapeutic preventive footwear is somewhat effective but remains a passive device. Surveying all current solutions reveals a technology gap for an ulcer prevention measure that is more effective and preemptive. Many research and commercial development has attempted in-shoe pressure sensing solution but these solutions suffer from inherent issues of analog sensor, hefty price tag and decreased relevancy in countries or seasons where covered shoes are less wore. We approached the problem with fabric digital switches to create a sensor-feedback wearable system to provide continuous, real-time detection and monitoring. A proof-of-concept is constructed and showcased to SGH collaborators as a demonstration of feasibility. The collaborating podiatrists acknowledged the potential but also reiterated the importance of analog pressure reading, which we planned to explore by digital estimation. The product is then developed through two iterations of wearable prototypes which include a wearable bootie laden with five digital sensors, a microcontroller platform with recording and Bluetooth capability and a companion smartphone application for data visualization and user interaction. Usability test of 5 days was conducted by SGH podiatrists then a focus group discussion is held. Although overall positive feedback is given on the prototype, the lack of analog pressure reading became the biggest shortcoming as that disallowed podiatrists to investigate the relationship of pressure to DFU formation, which in turn prevented a threshold of time-pressure integral or peak pressure be established. Meanwhile, data analysis on the digital pressure assertion pattern showed promising potential for frequency tracking and user activity recognition. Acknowledging the limitation of current prototype, the next development would investigate the possibility of approximation by digital sensors to actual reading from analog pressure sensors by building three different versions of prototype: fully analog-based, fully digital-based with accelerometer and a hybrid implementation of analog and digital. Other future works like development of scalable data analysis algorithm, addition of thermal sensor, and possible split development of patient device and medical apparatus are also identified. Finally, a few foundation works completed for future development are discussed, including the characterization and selection of appropriate sensor, the assessment of sample plantar pressure and the modular platform designed for next iteration. In conclusion, the dominant design that could fulfill all design considerations gathered based on researchers’ technical understanding and podiatrists’ clinical experience has yet to be achieved. However the development completed in this thesis has provided valuable foundation that not only helps to navigate the possible development directions but also allows future development to rapidly build upon. With luck, a successful design implementation could emerge in the next 1 – 2 years that leads to better quality of life and lower healthcare cost for the greater diabetic population.