Design and performance of a wireless pressure sensing stent

This paper reports the first time wireless performance of the previously reported pressure sensing stent [1-2]. Previously we reported only optical and electricallytethered measurement [1]. This paper reports the first time wireless measurement data with improved fabrication control. Specifically, this paper reports (1) the accurate control of evaporation to define the filling distance (54μm) of a hydraulic liquid (glycerol) in a microchannel (Fig.2b) and (2) wireless measurement of fluid flow pressure in a tube by utilizing the fabricated pressuresensing stent (Fig.4). The liquid amount, which was encapsulated to enable the hydraulic amplification ratio, was controlled with accuracy of ±10.51% by the newly modified method. The new method resulted in liquidfilling efficiency as low as 10.88μm/min via controlled evaporation at 90°C, 0.32Torr. The fabricated wireless pressure sensing stent demonstrated successful sensing of surrounding fluid pressure between 0 and 260mmHg, in a resolution of 5.42fF/mmHg over a distance of 2cm and at power consumption of 165μW/cm
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, in connection to an external capacitor of 30fF. The center frequency was measured as 79.668MHz.