Portable EGG recording system based on a digital voice recorder

Cutaneous electrogastrogram (EGG) recording offers the benefit of non-invasive gastrointestinal diagnosis. With long-term ambulatory recording of signals, researchers and clinicians could have more opportunities to investigate and analyse paroxysmal or acute symptoms. A portable EGG system based on a digital voice recorder (DVR) is designed for long-term recording of cutaneous EGG signals. The system consists of electrodes, an EGG amplifier, a modulator, and a DVR. Online monitoring and off-line acquisition of EGG are handled by software. A special design employing an integrated timer circuit is used to modulate the EGG frequency to meet the input requirements of the DVR. This approach involves low supply voltage and low power consumption. Software demodulation is used to simplify the complexity of the system, and is helpful in reducing the size of the portable device. By using surface-mount devices (SMD) and a low-power design, the system is robust, compact, and suitable for long-term portable recording. As a result, researchers can record an ambulatory EGG signal by means of the proposed circuits in conjunction with an up-to-date voice-recording device.