# ReFlex, a prosthetic hand that chooses its grip

> A prosthetic hand prototype that moves on EMG muscle signals, picks a grip with a palm camera and a model on a Raspberry Pi 5, and stops on encoder feedback.

Page: https://www.whitehatdesignstudio.com/work/reflex/
Published by: WhiteHat Design Studio
Last updated: 7 November 2026

Research prototype, assistive robotics

A research prototype of a prosthetic hand that starts moving on the wearer's muscle signal and uses a camera in the palm to choose the grip.

A hardware, C AI

![The ReFlex hand, a pale flexible hand on a dark forearm sleeve with a small camera in its palm, reaching towards a person's hand.](https://www.whitehatdesignstudio.com/_astro/reflex-hand.B3qEVWRT_Z26s7uI.jpg)

The hand, with the camera in its palm.

## What is ReFlex?

ReFlex is a research prototype of a prosthetic hand, designed and built by WhiteHat Design Studio. The hard part of a hand is not any one input. It is coordinating three: what the wearer intends, what the object in front of them is, and where each finger actually is. ReFlex connects the mechanical design, the electronics and the control software into one working loop on the bench.

The fingers are 3D-printed in TPU 95A, a flexible material, and pulled closed by strings, much as tendons close a hand. A custom sleeve holds the assembly on the forearm.

- **Type:** Research prototype
- **Built by:** WhiteHat Design Studio
- **Sector:** Assistive robotics
- **Inputs:** A hardware, C AI
- **Built with:** Raspberry Pi 5, MobileNetV2 on TensorFlow Lite, EMG sensing, encoder feedback, TPU 95A printed fingers, Fusion 360, SolidWorks, Prusa Slicer, Python, C and C++
- **Does:** Reads forearm muscle signals, chooses a pinch or tripod grip from what the palm camera sees, and stops each finger on encoder feedback.

## How ReFlex works.

### Calibrate

At start-up the hand calibrates to the wearer's EMG signal and sets its threshold.

### Sense intent

An EMG sensor reads forearm muscle activity. A moving average smooths it, and a change above the threshold starts a movement.

### See the object

If the hand is open, the camera in the palm looks at the object. A custom-trained MobileNetV2 model, running through TensorFlow Lite on a Raspberry Pi 5, chooses the grip, such as pinch or tripod.

### Close and stop

The motors for that grip drive the string-driven fingers closed, and each one stops when its encoder reaches its limit or the finger stalls.

### Open

The next signal drives the motors back until the fingers reach their rest position.

![The ReFlex hand standing upright on a laboratory bench, with test instruments behind it.](https://www.whitehatdesignstudio.com/_astro/reflex-lab.CR2dVArb_Z17BejL.jpg)

The laboratory prototype on the bench.

## Questions about ReFlex

### What is ReFlex?

ReFlex is a research prototype of a prosthetic hand, designed and built by WhiteHat Design Studio. It starts moving on the wearer's muscle signal and uses a camera in the palm to choose the grip.

### How does ReFlex choose a grip?

The camera in the palm looks at the object, and a custom-trained MobileNetV2 model, running through TensorFlow Lite on a Raspberry Pi 5, chooses a grip such as pinch or tripod.

### Is ReFlex a medical device?

No. ReFlex is a laboratory research prototype. It is not a medical device.

## Recognition

- Two conference papers at ICRAI 2024, on soft robotic fabrication with embedded vision and on a lightweight network for grasp classification.
- An appreciation award at COMPECC for the intelligent prosthetic hand.

## What we do not claim

- ReFlex is a laboratory research prototype. It is not a medical device.
- Grip accuracy is not quoted here.

## Sources

- [TechXpert engineering portfolio, ReFlex](https://www.techxpert.io/portfolio)

Published 5 November 2026, updated 7 November 2026.

## Read further

- [Hardware: robotics and embedded systems design](https://www.whitehatdesignstudio.com/services/hardware/)
- [AI: computer vision and edge AI](https://www.whitehatdesignstudio.com/services/ai/)
- [Edge AI or cloud AI: where should your model run?](https://www.whitehatdesignstudio.com/guides/edge-ai-vs-cloud-ai/)
- [How to turn a prototype into a product](https://www.whitehatdesignstudio.com/guides/prototype-to-product/)
- [Why a vision model that works in the lab fails in the field](https://www.whitehatdesignstudio.com/guides/vision-model-lab-to-field/)

## Tell us what has to work.

One sentence is enough. An engineer will reply.

[Talk to an engineer](https://www.whitehatdesignstudio.com/contact/) [WhatsApp an engineer](https://wa.me/923112721007?text=Hello%20WhiteHat%20Design%20Studio%2C%20I%20would%20like%20to%20talk%20to%20an%20engineer%20about%20my%20project.)