Electro-optic acquisition system for ECG wearable sensor applications

Abstract In the past few years a remarkable progress has been made in the design of sensors for wearable devices. Nevertheless, the existent devices are difficult to integrate, mainly due to the quantity of electrical interconnections and components required at the sensing places. This leads to the need for a new generation of wearable sensors. Photonic sensors have been presented in the medical field as a valuable alternative where power supply, electromagnetic interference and integration constitute a challenge. Therefore, this paper presents an electro-optic (EO) acquisition system designed for wearable Electrocardiogram (ECG) monitoring devices. The system includes a Lithium Niobate Mach-Zehnder Interferometer (MZI) modulator as the sensing element, and an optoelectronic signal conversion and processing stage. Tests were made in order to evaluate system performance in terms of signal amplification and sensitivity, frequency response and linearity. Obtained results have shown a suitable sensor's sensitivity of 20 μV and a frequency response of 60 dB flat from 0.2 to 40 Hz. Clinical sensor's performance was tested considering the requirements for evaluation of ECG. Results were compared with clinical standard electronics. Clear ECGs can be obtained with the EO sensor, showing adequate and reliable clinical performance. This EO sensor can be integrated into wearable materials being a suitable alternative for clinical cardiac monitoring.