Photodiode Finger Rehabilitation Device
Photodiode Finger Rehabilitation Device
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Using Novel Light Sensing Technology to Map Finger Motion for Enhanced At Home Physical Therapy Rehabilitation
Using Novel Light Sensing Technology to Map Finger Motion for Enhanced At Home Physical Therapy Rehabilitation
Role: Mechanical Design and Fabrication Lead,
Timeline: August - December 2024
Tools/Focus: Biomedical Robotics, Research, Arduino, Rapid Fabrication
Nearly 4 million stroke survivors in the US suffer from hemiparesis (partial paralysis of the body). The Photodiode Finger Replication Rehabilitation Device introduces a novel tool for rehabilitation methods through a lightweight, light based method of measuring movement. This device is designed for patients with limited finger mobility in one hand and full capabilities in the other. The device reads the bending angle in the healthy “Leader” finger and facilitates imitated bending on the disabled “Follower” finger. The goal of this project is to allow users to be self led in their rehabilitation practices through an effective and intuitive tool.
Exploring and Expanding Upon Existing Biomedical Robotics Research
Exploring and Expanding Upon Existing Biomedical Robotics Research
Initial brainstorming ideas- looking to existing technologies (left) and ideating on how to integrate different tools to create the most effective device (right). A potential idea discussed was utilizing pneumatics (air pressure), but found that pneumatics did not apply enough precise force for our uses.
In a team of 3, we sought to fill a gap in rehabilitation for patients with uneven loss of functionality in hands and fingers. We explored various methods of position measuring devices, including pressure sensors and EMG sensors, but found that photodiodes were most accurate and dependable in precise measurements. By measuring the deviation of a light beam as a healthy finger bends, the voltage loss across the tubing was used to approximate the finger’s bending angle—an innovative application of light sensing for finger rehabilitation. This measured angle was imitated via a cable-driven system on the weakened “Follower” finger to recreate an ideal range of motion. We chose to use a stepper motor to control the Follower finger because it provided precise, continuous motion and ideally small dimensions.
Prototyping and Building a Wearable Photodiode and Motorized Exo-Skeleton
Prototyping and Building a Wearable Photodiode and Motorized Exo-Skeleton
Early stage photodiode on finger: a photodiode reads light intensity from an LED as light travels along a clear plastic tube on index finger. Loss of light can be translated to an angle value.
A flaw of the the cable driven actuation was the unnatural bending angle on the Follower finger. To optimize the mobility of the Follower finger, we designed and 3D printed an exoskeleton, based on human joint anatomy, to most accurately replicate joint bending.
CAD model of exoskeleton for Follower finger, designed to accurately allow full bending at each joint.
Completed Photodiode Finger Rehabilitation Device with a) Leader Glove (photodiode sensor) and b) Follower Glove (3D printed exoskeleton, cables, and motor).
The final testing of this device found the bending angle of the Follower finger (weakened finger) to a degree within 10.6% error of the Leader finger (healthy finger). In the realm of rehabilitation this is considered successfully effective for regaining general mobility in a weakened finger.
Final Results and Finished Product
Final Results and Finished Product
Resulting angle readings of the Leader Glove in blue and achieved angle of Follower Glove in orange. The bending angles of Leader finger were 103.2 and 60.6 degrees, while the Follower Finger achieved bending angle of 95.2 and 52.4 degrees.
Outtakes from video of finished product, where flexion on the Leader Finger (right hand) causes imitated bending on Follower Finger (left hand).
As a mechanical engineer, this project and course opened a new world of human health centered design, something I never delved in before. I was enthralled to see that mechanical engineering can be applied to such an array of tasks and feel that this base of knowledge sets me up well to take on many challenges.
Final Report.pdfPage updated
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