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Low-cost robotic prosthetic hand

A design for a myoelectric hand: EMG sensors read the muscle signal and servos move 3D-printed fingers, sized from my own hand. Modelled in SolidWorks and analysed; not built.

Concept ✓ 2021

  • EMG
  • 3D printing
  • Servo actuation
  • SolidWorks

How the hand would work

A design for a myoelectric hand that costs a fraction of a commercial one. Pick a stage to see what it does, or pull the parts apart.

From muscle signal to fingerEMG sensors read the signal of the forearm muscles, a microcontroller turns it into commands, servos move the joints and the fingers close. This is the CAD design of my 2021 report at Universidad de Boyacá. I did not build it.Design stage: the hand was modelled in SolidWorks and analysed, not built or tested. The figure draws the design of the report; the control box and the wiring are schematic.

The problem

A prosthetic hand is out of reach for many people: a purely mechanical one that only opens and closes costs 2,000 to 5,000 USD, and a more complex one can reach 10,000 USD.

What I built

Lead Researcher, SIROM research group.

Stages reached

  1. Concept ✓ 2021

Result. Design cost target of 200 to 800 USD to produce (taken from Coogley, 2018), against 2,000 to 5,000 USD for a commercial mechanical prosthesis. The hand was not built or tested.

Inside the product

Project showreel (19 s).
Exploded animation of the phase 3 assembly (13 s).
CAD render of the full prosthetic hand
CAD render of the full hand.

From my own hand to the sketch

The first phase of the design, in 2021. I measured the back of my own hand, finger by finger, and drew it in SolidWorks so the prosthesis would match a real hand.

Dimensioned 2D sketch of the hand
My measurements: the length of each phalanx and metacarpal, in centimetres.
Outline of the hand built on the measurements
The outline of the hand built on those measurements.
Sketch of the hand with rounded shapes
The same sketch with rounded shapes, ready to turn into solids.

Joints and wrist

Before modelling in 3D I drew how the phalanges would join and how the wrist would move. A flexible metal piece and a plain screw join the phalanges, and four servos around the wrist were meant to tilt and turn the hand.

The phalanges as 3D solids on the sketch
The phalanges as 3D solids, drawn over the sketch.
Joint between the phalanges with a metal piece and a screw
Joint between the distal, middle and proximal phalanges: a metal piece and a plain screw.
Sketch of the wrist movement
Sketch of the wrist movement, with servos at the sides and on the palmar and dorsal faces.

The phase 3 assembly

The full hand as a CAD assembly: a wrist with two large joints, gears in the palm and five articulated fingers. It was designed, not built.

CAD assembly of the full hand
Full assembly of phase 3, with placeholder fingers: wrist, gears in the palm and the five fingers.
Frame of the exploded view with a gear
A frame of the exploded view: a gear and other parts before the assembly.
Frame of the exploded view with finger parts
Another frame: the parts of the fingers, separated.

Viability: what is known and what is open

The hand is a design from a 2021 report, not a product. This table separates what the report shows from what it does not.

Viability: what is known and what is open
QuestionWhat the report showsStatus
What is the gap?A purely mechanical prosthetic hand that only opens and closes costs 2,000 to 5,000 USD, and complex ones with AI reach 10,000 USD.Cited
What is the cost target?200 to 800 USD to produce, taken from Coogley (2018). It is a requirement from the literature, not a calculation of mine.Target, not validated
What must it do?Weigh under 500 g, close fully in 0.5 s or less and run for 30 minutes.Requirement, not tested
Was it built?No. It was modelled in SolidWorks and analysed.Design only
Who would use it and how would it reach them?The report describes the problem for people with limb loss and compares designs already on the market, such as Open Bionics. It has no user testing and does not cover regulation or a business model.Not studied