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Maximilian Mahal, David Kaltenbach, Lucas Rex. 

All Rights Reserved.

Design by Romy Strasser.


David Kaltenbach, Maximilian Mahal und Lucas Rex, GbR





c/o Heap 59

Erkelenzdamm 59

D—10999 Berlin


Shortcut - 

The Digital Prosthesis


Shortcut is the first Human Interface Device worldwide that is designed for people wearing a Prosthesis.


People with prostheses are limited in their use of digital hardware: mouse, keyboard and touchscreen are not built to match their needs. However, amputees are able to address movements of their phantom hand with the remaining muscles in their arm. Possibilities arise by creating a link between arm musculature and digital Interfaces. 

Shortcut is a wristband that is worn on the prosthesis. It translates gestures of the phantom hand into a contactless computer control. Thus the hand that has been lost is reactivated digitally and is able to reach into the virtual realm. Muscle patterns are translated into clicks, scrolls and shortcuts. This offers greater freedom in the workplace and beyond.



A majority of the muscles that move the hand are located in the lower arm. When a muscle contracts, electrical voltage is created.


Every week five people loose their hand on average, in Germany alone.


In spite of losing the hand, muscles in the arm stay intact. It is still possible to adress muscle movement patterns of the so-called phantom-hand.


The majority of amputees is wearing prosthetics. There’s a variety of models, with myo-electric prostheses being a common option.


Myoelectric prosthetics use my-sensors on the skin to read out voltages of muscle contractions. These signals are then translated into motor movements. In that way the prosthetic hand can for example open and close or turn.


Shortcut is a wristband that is worn on the prosthesis. It creates a new interface between prosthesis and computer.


The myoelectric signals of the prosthesis are transmitted wirelessly to Shortcut and are translated into computer commandos. They are then transmitted to the computer via Bluetooth to be executed.


The wristband also includes an optical sensor to read out planar movement son the tabletop surface, similar to a mouse. These sensor-values are translated into cursor movements and also sent to the computer. Shortcut works plug’n’play, no additional software is required.


The design is based on a repertoire of gestures that most amputees can address neurologically. These were mapped to the most relevant computer interactions in a sensible way. We have developed a catalogue of gestures that includes both basic functions such as cursor movement, left- and right-click and scroll, as well as shortcuts to functions such as zoom and quit. Thanks to a user-centered design approach the controls can be learned quickly and intuitively.


Left Click

Right Click



Zoom in/out

Scroll up/down


About Us

Maximilian Mahal

Max is a product designer with a background in craftsmanship and a strong expertise in rapid prototyping.

David Kaltenbach

David is an interaction designer. He has a great sense for generating wild ideas and turning them into reality. He has a strong eye for visuals.

Lucas Rex

Lucas is an interaction designer and a committed user advocate. He’s a fan of pragmatic solutions and design sprints.

Uli Maier

Uli is a prosthetics expert with many years of experience as an orthpedic technician for Ottobock Healthcare AG and Charité Berlin.

Shortcut is a project by Boost – we’re an interaction design studio based in Berlin. We’re receiving essential help from orthopaedic technician Uli Maier . The concept is work in progress, currently being supported by Ottobock. We are very open for feedback, and we’re currently looking for user-testers. Please drop us a mail – we’d be happy to hear from you :)

We are receiving funding from the EXIST scholarship program of BMWi and ESF and we’re alumni of the DesignFarmBerlin and AtomLeap accelerator programs. Shortcut was also awarded the STARTS Prize by Ars Electronica in 2016.