A musician with a prosthetic arm has told of his excitement at successfully hacking the device so he can control instruments with his mind.
Bertolt Meyer, a German psychology professor who moonlights as a DJ and techno producer, was born without the lower half of his left arm.
He spent his childhood wearing a hook connected to a harness but in 2009 was fitted with an ‘i-limb’, a state-of-the art prosthetic hand developed by Scottish company Touch Bionics.
The 43-year-old became an advocate for assistive technology, starring in Channel 4 documentary How to Build a Bionic Man and appearing on TEDx and other platforms to fight stigma around prosthetics.
Although he couldn’t be happier with the i-limb for day-to-day life, he struggled with the fiddly knobs and precisely-timed tweaks that are every electronic musician’s bread and butter.
‘The prosthesis picks up signals from picks up signals from the surface of my arm to control the hand, which I use to control the synths.
‘I thought: this is a bit of a stupid detour, can’t I just plug the signal from my arm directly into the synth, without having to convert it into physical motion?’
Bertolt developed a replacement unit through which he can plug himself into any modular instrument with just a cable.
The Chemnitz University professor has no formal background in engineering but used his knowledge of hobby electronics to develop a first prototype.
An electrical engineer from Berlin-based synth company KOMA helped turn the design into a more elaborate model, having a custom circuit board etched in China.
Bertolt’s husband Daniel, an artist and architect, used his 3D printer to make an adapter to attach the unit to his wrist.
The part-time producer says he can now mould his sound intuitively by hooking up his prosthesis to the myriad of inputs in his studio gear.
Although the unit is controlled by tiny impulses in his arm muscles, a decade of training makes it feel as if his mind is controlling the music directly.
‘It feels just like moving your fingers – you know how to do it, it’s effortless, but you can’t explain it.’
‘I’ve been wearing a prosthesis that works like this for more than 10 years every day, morning to evening, so for me it’s second nature.’
He said the biggest challenge was fine-tuning the electronic signals coming from his prosthesis, which he had to reverse-engineer without any help from the Scottish manufacturer.
‘I’m not sure they’d be happy about it – I took off their hand and made my own mods, probably violating a lot of safety requirements in the process!’
The technology is simple enough to have a wide range of applications, Bertolt explains.
‘The circuitry is not that difficult – I have an interest in electronics and DIY but not expertise, and even I can understand it.’
‘I’m also not the first person to think about using muscle signals to control technology.’
A short-lived project by Canadian company Thalmic Labs produced the Myo, a removable armband that uses electrical activity in the muscles to control drones, computers and smartphones.
It was discontinued in 2018 in favour of other projects, but has been used by EDM DJ Armin Van Buuren to control lights and stage effects during performances.
Back in 1965, American experimental composer stunned the fledgling world of electronic music when he gave a performance controlled by brain waves picked up from electrodes stuck onto his forehead.
His use of low-frequency thumps to activate percussion instruments was groundbreaking at the time. But it looks crude in comparison to Bertolt’s new gadget, which he’s calling the Synlimb.
Bertolt buzzed with excitement at the prospect of redesigning his music performances.
‘It will probably take a couple more iterations until it’s finished, but I envision playing music only with this device and not my main prosthesis.
‘I also plan to release the design as an open-source product, for the few people like me who have partial limbs and are into electronic music.’
A full explainer can be viewed on Bertolt’s YouTube channel.