32 Leads Eeg Acquisition System Hardware Design

In numerous ways to study the cognitive function of the brain, PET, fMRI, MEG and other equipment plays a very important role, compared to these expensive devices, digital EEG is favored by researchers and clinicians in the study used routine diagnostics for its millisecond even microsecond level high time resolution and lower cost for equipment purchase and maintenance.At present, the majority of domestic and international mainstream EEG acquisition products using AC coupling, the system bandwidth is typically 0.5Hz ~ 100 Hz. With the development of the study, in the vicinity of the low frequency near DC and high frequency 1000 Hz, it was confirmed that these areas contain useful information about the disease. With the development trend of EEG studies, a bandwidth of DC ~ 1000 Hz 32-channel EEG acquisition system is designed.The hardware part of 32 channel EEG acquisition system is designed as board structure, there are one master board and four high-performance 8-channel EEG acquisition hardware circuit boards, which is divided into analog and digital Circuit sections. Analog portion uses auto-zeroing and chopping technique ping-pong configuration and monolithic op amp instrumentation amplifier, combining DAC to form part of a DC-coupled preamplifier functions, and uses the state variable type integrated chip built-frequency notch circuit. The digital part comprises a microcontroller, isolation circuit, and an impedance detection circuit. Master board section constitutes the main DSP and USB responsible for communication with the host computer, while controlling four EEG acquisition board.This paper conducted a preliminary test in accordance to standard digital EEG JJG954-2000 national standards GB9706.1 key, while using typical experimental verification EEG acquisition system feasibility test, results show that the designed 32 channel EEG acquisition system performance is good, and can be used to study brain function and clinical diagnostics.