Bluetooth Low Energy-powered wearable uses drug-free nerve-stimulation technology to treat a range of chronic pain conditions

NeuroMetrix’s ‘Quell 2.0’ wearable

NeuroMetrix’s ‘Quell 2.0’ wearable employs Nordic’s nRF52832 SoC allowing users to wirelessly control and personalize their device from a smartphone 

Nordic Semiconductor today announces that NeuroMetrix, a Waltham, MA-based medical technology company, has selected Nordic’s nRF52832 Bluetooth® Low Energy (Bluetooth LE) System-on-Chip (SoC) to provide the wireless connectivity for its ‘Quell 2.0’, a wearable device for the treatment of chronic pain.

Quell 2.0 is a clinically tested, 100 percent drug-free system that uses prescription-strength nerve-stimulation technology to block pain signals in the body. Quell is designed for people with a wide range of chronic pain conditions including pain involving the feet, legs, and lower back. The slim, lightweight, easy-to-wear device works by stimulating sensory nerves in the patient’s calf. The nerves then carry neural pulses to the user’s brain which triggers a natural response to block pain signals in the body. According to the developer, Quell is the only non-prescription pain relief device cleared for use while sleeping by the U.S. Food and Drug Administration (FDA).

Nordic’s nRF52832 SoC establishes Bluetooth LE wireless connectivity between the Quell 2.0 wearable and the user’s Bluetooth 4.0 (and later) smartphone, where the user can access NeuroMetrix’s free iOS and Android companion app, ‘Quell Relief’. Enabled by the Bluetooth LE link, the app allows the user to wirelessly calibrate the Quell 2.0 device to their personalized therapeutic intensity, start or stop therapy, adjust intensity level, track sleep, activity, pain and gait, and take advantage of a variety of other settings to meet their unique pain relief needs.

Quell 2.0 contains a rechargeable 500mAH Li-Ion battery. While the device’s battery life is heavily dependent on each user’s particular therapy intensity and frequency of use, a fully charged battery can last up to 25 therapy sessions (60 minutes per session), thanks in part to the low power characteristics of the nRF52832 SoC. In operation, the therapy component of Quell 2.0 consumes the highest level of power, however the ability to minimize power consumption through the Nordic SoC’s power-saving sleep mode when the device is not actively running therapy, has enabled the developer to significantly reduce the overall form factor of the wearable as compared to the previous generation device.

Minimizing size is a key driver of the design, so the ability to have an integrated processor and Bluetooth LE system on a single chip was very important
Andres Aguirre, NeuroMetrix

Nordic’s nRF52832 multiprotocol SoC combines an 64MHz, 32-bit Arm® Cortex® M4F processor with a 2.4GHz multiprotocol radio (supporting Bluetooth 5, ANT™, and proprietary 2.4GHz RF protocol software) featuring -96-dB RX sensitivity, with 512kB Flash memory and 64kB RAM.

The SoC is supplied with Nordic’s S132 SoftDevice, a Bluetooth 5-certifed RF software protocol stack for building advanced Bluetooth LE applications. The S132 SoftDevice features Central, Peripheral, Broadcaster and Observer Bluetooth LE roles, supports up to twenty connections, and enables concurrent role operation. Nordic’s software architecture, which includes a clear separation between the RF protocol software and the customer’s application code, allowed NeuroMetrix developers to develop, test, and verify their application code within a simpler and safer development framework.

 “The nRF52832 SoC offered multiple features that were advantageous for our application,” says Andres Aguirre, Senior Algorithm and Software Engineer at NeuroMetrix. “As a wearable, minimizing size is a key driver of the design, so the ability to have an integrated processor and Bluetooth LE system on a single chip was very important to reduce our PCBA [Printer Circuit Board Assembly] footprint.

“The powerful M4F processor and high amount of Flash and RAM made the Nordic SoC a strong contender for our application, while the final decision to select the nRF52832 was based on availability and price. As a company, Nordic provided helpful field application engineers, online assistance, and numerous SDK [software development kit] examples.”