ReFlex Band

Background

Stroke is one of the leading causes of long-term disability in the United States. One of the most common outcomes is hemiplegia or hemiparesis, partial or complete loss of motor function on one side of the body. For many survivors, regaining arm and hand function is the single most important rehabilitation goal, and one of the hardest to achieve.

The Tufts IDEA Human Factors Lab brought me in as a graduate researcher to investigate this problem space, studying the biomechanics of the affected limb and helping design a device that could assist with motor recovery outside of formal therapy sessions.

Problem

Rehabilitation after stroke is intensive, expensive, and time-limited. Patients receive a few hours of formal therapy per week, but the research is clear that neuroplasticity and motor recovery require consistent, repetitive movement practice throughout the day, not just during clinic visits.

The problem: most assistive devices for stroke rehabilitation are either bulky clinical equipment that can't leave the hospital, or passive braces that don't actively facilitate movement. There's a real gap for something lightweight, wearable, and capable of assisting voluntary muscle activation, something a patient could use at home.

The ReFlex Concept

The ReFlex band is built around a bi-stable mechanism, a structure that has two distinct stable states and snaps between them with relatively little force. This property is central to the design: a patient with limited muscle strength can initiate a small movement, and the bi-stable element amplifies that movement into a full functional gesture.

Think of it like a hair tie with a spring memory. The device wraps around the forearm, senses voluntary muscle activation, and responds by completing or assisting the movement the patient is trying to make. The goal is a feedback loop that reinforces motor patterns, the same mechanism the brain uses to rebuild neural pathways after stroke.

My work focused on the human factors side of this: understanding the range of arm geometries and muscle activation patterns we needed to design around, prototyping early physical forms, and helping design the user studies that would inform the next iteration of the device.

Process

The project ran through the full 2023–2024 academic year with weekly structured team meetings at Tisch Library. My contributions spanned the research and early prototyping phases:

• Reviewed existing literature on bi-stable mechanisms, wearable rehabilitation devices, and stroke motor recovery
• Conducted biomechanical analysis of forearm and wrist motion to establish design constraints
• Built and tested early physical prototypes of the bi-stable band structure
• Designed mixed-methods study protocols for administering behavioral and sensor-based data collection
• Processed and visualized sensor and time-series datasets using Python to translate findings into design guidelines

What I Learned

This project deepened my understanding of what it means to design for a clinical population. The constraints are different from consumer product design in almost every way, the stakes are higher, the user population is more variable, and the path from prototype to patient is long and rigorous.

It also reinforced something I keep coming back to: the most important work in human factors happens before you pick up a tool. The biomechanics analysis, the literature review, the study design, that's where the real design decisions get made. Everything downstream is execution.

I came into graduate school knowing I wanted to work at the intersection of physical design and human behavior. The ReFlex project showed me what that actually looks like in practice, and made me want to go deeper.