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BlueGain

BlueGain biomedical amplifiers are a range of wirelessly connected amplifiers for directly measuring patient bio-potentials. BlueGainEOG has been configured to record electrooculograms (EOG) and communicate these signals via Bluetooth to a host computer, performing the minimum amount of processing. An infrared sensor allows data to be synchronised with external events.

Electrooculography is an electrical method of recording eye movements. Tiny electrodes are attached to the skin at the inner and outer corners of the eye, and as the eye moves an alteration in the potential between these electrodes is recorded. The size of this potential at rest also gives an indication of the health of the retina. The recording itself is called an electrooculogram (EOG).

In some situations it can be difficult to accurately tie external event indicators to the recorded analog data stream particularly when a stimulus generator and the recording device are operated independently. To help with this, BlueGain implements a separate infra red marker channel that operates without destroying the benefits of wireless communication. A supplementary unit connected to the stimulator generates infra-red pulses that are received by a sensor located on the front of the BlueGain unit and recorded as events directly into the data stream with a resolution of 100µs.

Each data point in the BlueGain system is stamped with its sample time so that the host computer can verify the integrity of the data stream. A 3 second on-board memory provides temporary buffering in the event that data transmission is delayed by the host computer thereby ensuring that data will only be lost in exceptional circumstances. Battery life is extended by an auto power down feature that turns the system off after data transmission has been completed.

Each of the analog input channels is amplified by a high quality instrumentation amplifier before being simultaneously sampled and digitised with 16bit resolution at 10kHz. BlueGain's flexible signal processing scheme means that all large blocking capacitors and other unreliable discrete elements have been completely removed from the signal path resulting in even better fidelity. The high intrinsic over sampling rate of the ADCs allows multiple samples to be accumulated before transmission to the host computer giving a further two bits of signal resolution.

In the BlueGain philosophy, the analog signals are amplified then digitised directly within the range DC to the maximum pass frequency of the system. All subsequent signal processing such as DC removal and 30Hz low pass filtering is performed digitally by the host computer. This means that you are completely in control and never stuck with incorrect algorithms or the wrong frequency response.

BlueGainEOG works with the minimum amount of disruption to a subject’s natural behavior. The wireless set up and arm band give complete freedom of movement without distraction.

BlueGainEOG uses a wireless Bluetooth connection to galvanically isolate the subject, along with touch proof electrode connections ensuring the device is completely safe to use for research.