Passive Backscatter Biotelemetry for Neural Interfacing

Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering Kohala Coast, Hawaii, USA, May 2-5, 2007  Wireless telemetry of  bioelectrodes can be accomplished over distances by using the biopotential to directly modulate the characteristics of a simple passive resonant circuit consisting of two varactor diodes and an inductor. Backscattered radio frequency energy at or near the circuit resonance in the 300 MHz region is amplitude modulated by the biopotential and detected by a remote receiver. - Miniaturization of radio transmitters for implantation in the human body still requires biotelemetry applications that induce high stress to excite neural spikes for both markers and comparison analysis to distinguish vowel /consonant/vowel representations in  recorded brain wave phase sensitive detection. The demodulator(the Encoding System) is constructed around a  frequency mixer. whose output is then amplified and bandpass filtered.-Bruce C.Towe  Mohseni, P, Najafi, K., Eliades, S. Wang, X., “Wireless Multichannel Biopotential Recording Using an Integrated FM Telemetry Circuit”, IEEE Trans. Neural Systems and Rehab Engineering, Vol 13, no3, Sept 2005. [2] Finkenzeller, Klaus, The RFID Handbook, John Wiley and Sons, 2003. [3] Towe, B.C., "Passive Biotelemetry by Frequency Keying", IEEE Trans. Biomedical Engineering, vol. BME-33, no.10, October 1986. [4] Wise, K., Anderson, D., Hetke, J., Kipke, D., Najafi, K., “Wireless Implantable Microsystems: High Density Electronic Interfaces to the Nervous System”, Proc. IEEE, vol. 92, no.1, pp.76-97, January 2004. [5] Tang, Z., Smith, B.,Schild, J., Peckham, H., “Data Transmission from Implantable Biotelemeter Load Shift Keying Using Circuit Configuration Modulato Troyk, Philip R., “Injectable Electronic Identification, Monitoring, and Stimulation Systems”, in Ann. Rev. Biomed. Eng., Vol 01:177-209, 1999. [7] Mass, W., Von Arx, J., “Passive Telemetry System for Implantable Medical Device”, US patent #6,889,086. [8] Microelectromechanical Systems, V ol. 9, No. 4, December 2000. Experimentally measured bandpass of the wireless circuit system . ECG waveform of about 1 mV amplitude from bioelectrodes on a human subject telemetered over a 10 cm distance using interface