An impedance wire integrated with flexible flow sensor and FFR sensor for cardiovascular measurements

This paper reports on an impedance wire with flexible flow sensor and FFR sensor integrated on its surface, which will allow, for the first time, minimally invasive in-vivo measurement of blood flow rate and fractional flow reserve (FFR) simultaneously. These two sensors are first constructed on parylene-C film into a single device, with gold electrodes and leading wires embed in it. With a total thickness of 8 μm, the device has extremely flexibility and can work well on a thin wire with a diameter of 380 um. The flow sensor and the FFR sensor are both based on electrochemical impedance (EI) transduction, The EI-based sensor is the first time employed for FFR determination. The capability of the two sensors was demonstrated in-vitro. A favorable linearity of the impedance/flow relation of the flow sensor was found over 0-250ml/min. The FFR sensor also exhibited high sensitivity at the range of FFR from 0.6 to 1.