In Ecuador, engineer Alfonso Espinoza Moran has developed an innovative myoelectric hand prosthesis. What makes it special: Almost all of the components were produced using additive manufacturing processes. Espinoza utilised various 3D printing technologies to produce the complex geometries of the prosthesis in a cost-efficient manner.
The FDM process with PETG filament was used for the main components. Smaller parts were produced from nylon using SLS, while intricate structures were created from synthetic resin using SLA. Espinoza produced particularly stressed mechanisms such as gear wheels from stainless steel using the SLM process.
The housing of the electronic hand posed a challenge. It had to provide space for five actuators, sensors and the control board, while at the same time being aesthetically pleasing. This is where the flexibility of 3D printing paid off.
The prosthesis works like commercial models from Europe or the USA: electromyographic sensors record muscle signals in the forearm. These are processed and control the movements of the artificial hand. Pressure, position and rotation sensors enable precise control.
The socket – the connecting piece between the prosthesis and the arm stump – is particularly customised. Espinoza scans each user’s residual limb and then prints a customised fit from PETG or ABS.
The project was well received by the city council of Guayaquil. It financed the production of 20 myoelectric prostheses for adults and four mechanical models for children. Espinoza also offered free 3D printing courses for the public.
Despite its success, the project ended after 15 months due to a change in government. Espinoza now hopes that a company will show interest in further developing his prosthesis.
The case shows the potential of 3D printing for the customised and cost-effective production of medical aids. At the same time, it highlights the challenges involved in the long-term financing of such projects in emerging countries.
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