Flexible Distributed Pressure Sensing Strip for a Urethral Catheter

Abstract

A multi-sensor flexible strip is developed for a urethral catheter to measure distributed pressure in a human urethra. The developed sensor strip has important clinical applications in urodynamic testing for analyzing the causes of urinary incontinence in patients. There are two major challenges in the development of the sensor. First, a highly sensitive sensor strip that is flexible enough for urethral insertion into a human body is required and second, the sensor has to work reliably in a liquid in-vivo environment in the human body. Capacitive force sensors are designed and micro-fabricated using polyimide/PDMS substrates and copper electrodes. To remove the parasitic influence of urethral tissues which create fringe capacitance that can lead to significant errors, a reference fringe capacitance measurement sensor is incorporated on the strip. The sensing strip is embedded on a catheter and experimental in-vitro evaluation is presented using a bench-top pressure chamber. The sensors on the strip are able to provide the required sensitivity and range. Preliminary experimental results also show promise that by using measurements from the reference parasitic sensor on the strip, the influence of parasitics from human tissue on the pressure measurements can be removed.

An Instrumented Urethral Catheter With Supercapacitor Based Force Sensor

“…As shown in Fig.5, the urethral sensor can measure a pressure as low as 0.5psi. The sensitivity of the sensor is estimated to be around 0.1nF/psi, which is at least 3 orders of magnitude more sensitive per unit area compared to traditional capacitive sensors [3]. The sensors can be used inside the human body and in body fluids without experiencing parasitic noise, since the parasitic noise inside human body is usually in the order of fF~pF.…”

“…pollute the sensor signal. The parasitic capacitance for in vivo use is of the order of femto or pico Farads according to previous research of our group ( [3,8,9]) and is hard to eliminate by estimation and subtraction.…”

A Flexible Optical Sensor for Microalbuminuria Spectroscopy

“…It has hydrophobic surfaces making it easy to attract protein molecule. PDMS is a low cost material, easy to fabricate and has good flexibility that make it suitable candidate for prototype of MEMS microalbumin detections [7]. The findings of this study is a breakthrough on microalbuminuria detection as a lowcost and flexible sensing material could determine the albumin level in urine with transmittance light variation and refractive index of light.…”

Sensor Fusion and Smart Sensor in Sports and Biomedical Applications

“…The set contains an array of capacitive sensors enclosed in a single system (smart), inserted into the urethra to measure its pressure [128]. Capacitive sensors were chosen because the application requires flexibility for insertion into the human body, in addition to the reliability of the measurement of liquids in an in vivo environment.…”