A plethysmographic sensor for monitoring volume changes in cardiovascular pathologies

This paper presents a capacitive system capable of performing leg volume change monitorization in patients suffering from Heart Failure (HF) conditions. The body volume evolution serves as a prognosis marker for this kind of patients, such patients can benefit from a wearable monitorization system. The proposal is based on a contactless capacitive wearable structure implemented by a two-plate plane-parallel capacitor geometry. The system exhibits sensitivity to leg volume change and the sensor curves are provided. A 2.5x2.5cm capacitive electrode design will generate capacitive values within the range [1-2] pF. Acquisition of the capacitance value is performed via an electronic differentiator implemented using op-amps, illustrating good results in simulated volume analysis implemented using pspice.