Figure 1. WiSEMG Wireless Surface Electromyography
1 Key Features
- High input impedance: 20 MΩ differential, 5 MΩ common mode.
- Large bandwith: 5 Hz - 500 Hz.
- 8-steps scope-scaled adjustable gain provides over 46 dB of regulation.
- CMRR exceeds 100 dB.
- 10 bit, 2 kHz ADC sampling.
- Optional 3-axes integrated accelerometer with selectable sensitivity of ±4g or ±12g.
- Radio link: IEEE-802.15.4 compliant physical layer, 2.4 GHz band.
- Proprietary highly-specialized radio protocol achieves latencies as low as 40 ms.
- Low-power: more than 8 h of continuous acquisition when powered by industry-standard rechargeable LIR2450 Li-ion batteries.
- Battery: pre-installed soldered LIR2450 or optional connector for external battery.
- On-board battery charger and monitor with coulomb counter for accurate residual run time prediction.
- 4.50 V to 5.25 V, 100 mA (max) charging input socket.
- PCB size: 41 mm x 26 mm, 12 mm height (with battery).
Cedar Solutions' CS-WMG-12001, an active electromyography sensor with integrated wireless transmitter, is the core of the WiSEMG system, which is comprised of active sensors, such as the CS-WMG-12001, that acquire, amplify, digitise, and wirelessly transmit the EMG signal to a base station (such as the CS-WMG-12002 or CS-WMG-12003) connected to a PC via an USB interface.
Up to 5 CS-WMG-12001 sensors can be managed by a single base station, and up to 16 base stations can be in operation at the same time in the same radio-coverage area.
The sensors are completely remotely operated from the PC: they are normally in a deep stand-by mode in which they draw an extremely low current from the battery, allowing for months of storage with-out depleting the battery. They are awaken on demand by the base station and, after a few seconds, become completely operational and ready to start the measurement, which is triggered from the PC.
The complimentary GPL-licensed software SD-WMG-32001 provides full control of the WiSEMG system. Acquired data is displayed in real time on the PC monitor and recorded in plain text les for later processing. Complete remote diagnostic of the sensors, including battery run time, is also available.