A wireless electroencephalogram telemetry recording system for roaming animals

A wireless portable electroencephalogram (EEG) recording system for animals is designed, manufactured and then tested in a rat. The system basically consists of four modules: 1) EEG collecting module with the wireless transmitter and receiver (designed by NRF24LE1), 2) filter bank consisting of preamplifier, band pass filter and 50 Hz trapper, 3) power management module and 4) display interface for showing EEG signals. The EEG data are modulated firstly and emitted by the wireless transmitter after being amplified and filtered. The receiver demodulates and displays the signals in voltage through serial port. The system is designed as surface mount devices (SMD) with small size (20 mm × 25 mm × 3 mm) and light weight (4 g), and is fabricated of electronic components that are commercially available. To test the system, measuring electrodes were implanted on the rat's skull and the acquisition transmitter was strapped on the back of the rat. Waveform recordings were carried out during waking state. The test results indicate that in given environment the system could stably record more than 8 hours and transmit EEG signals over a distance of 20 m. Our system shows the features of small size, low power consumption and high accuracy which is suitable for EEG telemetry in rats.