Wearable devices like smartwatches and fitness trackers provide detailed insights into our health and physical activities, offering a level of detail previously unknown to us. Not only do these insights give us the raw data we need to improve our well-being, but they can also be shared with medical professionals so that they have a better chance of detecting health problems earlier, and of offering better treatment plans for ongoing health conditions.
But these traditional self-tracking systems do not meet everyone’s unique needs. People with spinal cord injuries (SCI), for instance, are not well-served by them. Step counters and activity trackers are of little to no importance to these people, but a team of researchers at the University of Utah believes that a specially tailored monitoring system could significantly improve their health. So they set out to develop a system for monitoring the development of pressure ulcers, which are a serious — and somethings fatal — complication that can develop in people with minimal mobility.
Their solution, called the Tilt Tracker , is a self-tracking system designed to help individuals who rely on power wheelchairs for mobility. Unlike conventional fitness trackers, Tilt Tracker focuses on pressure relief (PR) adherence, a crucial aspect of care for people with severe SCIs. Pressure ulcers develop due to prolonged sitting without repositioning, making PR exercises essential for preventing these life-threatening wounds. However, due to the high frequency of required PR movements — up to 50 times a day — it is easy for wheelchair users to forget or miss these crucial repositioning activities. Tilt Tracker aims to solve this problem through real-time tracking, reminders, and feedback mechanisms.
The system was built around the Particle Boron IoT development platform, a compact and powerful module that enables wireless data transmission over LTE networks. This feature ensures that the system remains connected even when users are outdoors or otherwise away from Wi-Fi, providing continuous tracking and recording of data in the cloud. The Boron board is housed within a custom 3D-printed enclosure, approximately the size of a smartphone, which is mounted to the lower backrest of the wheelchair using removable double-sided tape.
The Tilt Tracker includes a multi-sensor setup to accurately detect PR movements and wheelchair occupancy. A DigiKey LSM9DS1 inertial measurement unit is installed under the seat pan, while an ADXL362 3-axis accelerometer is attached to the chair’s backrest. Together, these sensors measure the tilt of the chair and whether proper pressure relief exercises are being performed. Additionally, a force-sensitive resistor placed under the seat cushion detects whether the wheelchair is occupied.
The device features three reminder modalities to assist users in performing PRs: haptic (vibration), audio (buzzer), and visual (LED light). A small vibration motor is mounted on the headrest to provide a gentle nudge, while a piezo buzzer emits an audio cue when a PR is due. For visual feedback, an LED indicator is placed near the joystick area. These multiple modalities ensure that individuals with varying levels of mobility and sensory function can receive reminders effectively.
Tilt Tracker was tested in a rehabilitation hospital with nine inpatient participants, demonstrating its feasibility and effectiveness in improving PR adherence. Early results suggest that users became more aware of their PR routines and performed PRs more consistently when using the device.
This "chairable" system may be a glimpse into the future of assistive technology, where smart, adaptive monitoring tools can be tailored to meet the unique needs of different groups.
A high-level overview of Tilt Tracker (📷: T. Motahar et al.)
The system is built around a Particle Boron (📷: T. Motahar et al.)
