Nordic Semiconductor has revealed that the Compex Wireless, the world’s first wireless muscle electro-stimulator – as used by HTC-Highroad, the cycling team of top 2011 Tour de France sprinter Mark Cavendish – employs Nordic nRF24LE1 proprietary 2.4GHz SoCs.
Tour de France sprinter Mark Cavendish with his Complex Wireless
The Compex Wireless employs mechanical biofeedback (‘mi-SCAN’) technology to automatically and safely adjust the stimulation settings to the specificities of each muscle. Electro muscle stimulation has long been used by elite professional athletes both during training (to stress key target muscles) and between training sessions and competitive events (to accelerate recovery cycles and treat common intensive training ailments such as lower back pain).
According to Nordic Semi, the Compex Wireless is the world’s first electro-stimulator to the offer the convenience of wireless to maximise application freedom and comfort without the risk of users getting tangled up in trailing cables.
It also gives non-professional users the ability to access the benefits of muscle stimulation on a regular basis, by making it possible for them to set training objectives and download relevant muscle stimulation programs and ready-to-use schedules from a dedicated website.
In operation, a Nordic nRF24LE1 2.4GHz SoC with on-board microcontroller running a Compex-developed wireless networking protocol is located in each of up to four compact wireless circular stimulators (5.5cm diameter, 1.8cm thick, 50g weight). These communicate with another nRF24LE1 located within a wireless controller featuring a 6.1cm color LCD screen and simple user interface used to set up and control the Compex Wireless. Each stimulator can operate for an entire day between recharges from a built-in 450mAH lithium-ion polymer rechargeable battery under highly demanding (two training programs at high power and three recovery programs) usage conditions.
Nicolas Fontaine, R&D Team Manager & Senior Firmware Engineer at Compex Médical in Switzerland that developed the Compex Wireless, said in a statement: “Making this product wireless was a big challenge. For user comfort all stimulators have to be precisely synchronised within milliseconds of each other at all times and the whole wireless network demanded very low latency so that should the system need to stop [e.g. due to a low battery level in one of the stimulators or by instruction from the user], it stopped immediately and simultaneously rather than disorderly over a few seconds. Finally, the product had to work reliably even in challenging RF environments shared with other Compex Wireless users in close proximity (e.g. during races) and other active 2.4GHz sources such as Wi-Fi and Bluetooth wireless technology. We achieved all of this while meeting all relevant product specifications, compliances and regulations thanks to the dedication of our development team, and support from both Nordic and it’s local European distributor Rutronik.”
ECN Europe 