On the feasibility of self-mixing interferometer sensing for detection of the surface electrocardiographic signal using a customized electro-optic phase modulator.
Optical sensing offers an attractive option for detection of surface biopotentials in human subjects where electromagnetically noisy environments exist or safety requirements dictate a high degree of galvanic isolation. Such circumstances may be found in modern magnetic resonance imaging systems for example. The low signal amplitude and high source impedance of typical biopotentials have made optical transduction an uncommon sensing approach. We propose a solution consisting of an electro-optic phase modulator as a transducer, coupled to a vertical-cavity surface-emitting laser and the self-mixing signal detected via a photodiode. This configuration is physically evaluated with respect to synthesized surface electrocardiographic (EKG) signals of varying amplitudes and using differing optical feedback regimes. Optically detected EKG signals using strong optical feedback show the feasibility of this approach and indicate directions for optimization of the electro-optic transducer for improved signal-to-noise ratios. This may provide a new means of biopotential detection suited for environments characterized by harsh electromagnetic interference.
Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. ashrif@eng.ukm.my
A Ashrif A
AA
Bakar
Yah Leng
YL
Lim
Stephen J
SJ
Wilson
Miguel
M
Fuentes
Karl
K
Bertling
Thomas
T
Taimre
Thierry
T
Bosch
Aleksandar D
AD
Rakić
D018780:Body Surface Potential Mapping / Q000295:instrumentation*; D004562:Electrocardiography / Q000295:instrumentation*; D004581:Electronics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D006801:Humans; D007368:Interferometry / Q000295:instrumentation*; D055096:Optical Devices; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity