110 likes | 254 Views
MIAMI Medical Instrument Analysis and Machine Intelligence. www.ece.uwaterloo.ca/~miami. MIAMI. Quick presentation of “Results of micro-electrodes survey” Salam R. Gabran May 11 th 2005. MIAMI. MEMS and Bio-Sensors Team. Signals of interest. 2 methods of signal detection :
E N D
MIAMIMedical Instrument Analysis and Machine Intelligence www.ece.uwaterloo.ca/~miami
MIAMI Quick presentation of “Results of micro-electrodes survey” Salam R. Gabran May 11th 2005
MIAMI MEMS and Bio-Sensors Team Signals of interest 2 methods of signal detection : • EEG (electroencephalogram) • MEG (magneto encephalogram)
MIAMI MEMS and Bio-Sensors Team MEG (magneto encephalogram): • Detection using SQUID (super conducting quantum interface device) magnetometers • SQUIDs are super conductors and require cryogenic temperatures • The skull is more transparent to the magnetic fields emitted by the brain • “MEG and EEG record electric activity of the brain in a similar way” [Jaakko Malmivuo]
MIAMI MEMS and Bio-Sensors Team Conclusion on MEG: • SQUIDs (Josephson junction) are nano devices and the design can include quantum transistor amplifiers. • This technology is still evolving and requires further research • The Cryogenic nature of super conductors is a major drawback for our targeted device • This requires further survey
MIAMI MEMS and Bio-Sensors Team EEG (electroencephalogram): Types of electrodes:
MIAMI MEMS and Bio-Sensors Team Conclusion: Dry EEG electrode is the targeted device
MIAMI MEMS and Bio-Sensors Team EEG (electroencephalogram): Stages of dry electrode design: Stage 1: Electrode design and Micro-fabrication Electrode design: Design the shape of the pin array Electrode material: Non-toxic and compatible with the fabrication technology
MIAMI MEMS and Bio-Sensors Team EEG (electroencephalogram): Stage 2: Circuit design Pre-amplifier circuit: Electrode-preamp distance affects artifacts Filters: Including 60Hz notch filters Bio-amplifier: High CMRR (common mode rejection ratio) and high SNR (signal to noise ratio) to suppress artifact effects Usually designed using instrumentation amps
MIAMI MEMS and Bio-Sensors Team EMI Calibration and variable gain adjustment Faulty placement detection method 1: high impedance or open circuit detection method 2: signal strength window Micro-wires Required for connection between electrodes and other device elements Circuits and electrodes will be designed to share the same substrate or chip
MIAMI MEMS and Bio-Sensors Team Related papers “An active micro fabricated scalp electrode array for EEG recording” “Characterization of micro machined spiked bio-potential electrodes” “Characterization of a micro machined planar patch clamp for cellular electrophysiology” There are other papers discussing intracranial (brain penetrating) electrodes