In Vitro and In Vivo characterization of wireless and passive micro system enabling gastrointestinal pressure monitoring

Abstract

This paper presents a wireless and passive micro pressure system based on the LC mutual inductance detection mechanism for gastrointestinal (GI) pressure monitoring. The micro pressure system is composed of a sensor capsule (a pressure sensitive micro capacitive sensor in series with an induction coil to form an LC tank) and a detection unit (a detection coil connected with a network analyzer). The pressure variations under measurement lead to changes in the capacitance of the pressure sensor and therefore a shift in the LC tank resonant frequency, quantified by the impedance measurement of the detection coil. The pressure sensor was fabricated using microfabrication processes with key parameters optimized. The in vitro characterization of the micro pressure system recorded a sensitivity of 0.2491 kHz/kPa (-10 kPa to 30 kPa). One-month rabbit stomach pressure monitoring was conducted based on the developed micro pressure system as a confirmation of device long term in vivo stability. Furthermore, rabbit stomach pressure variations before and after food feeding was recorded and compared where three distinctive contraction patterns (random contraction with low amplitude, irregular strong contractions and regular contraction in a cyclic manner) following food feeding were located. Compared to previous reported GI pressure sensors, this LC tank is featured with simple device structure without batteries and electrical components for energy transfer. Both in vitro and in vivo characterization confirm the functionality of the system, which may enable the gastrointestinal motility study in the near future.

MRI-based communication for untethered intelligent medical microrobots

“…The system works without batteries and electrical components for energy transfer. The functionality of the system is confirmed by in-vivo and invitro experiments [36].…”

“…Several studies have also reported using a microrobot for endoscopy [27,28,36,37]. For instance, Iddan et al [27] reported a study presenting a new painless endoscopic imaging of the small bowel.…”

“…A micro pressure system is proposed in [36] to monitor gastrointestinal (GI) pressure. The system includes a sensor capsule which measures the pressure using a sensitive micro-capacitive sensor in series with an induction coil to form a LC tank.…”

Measurement of Gastrointestinal and Colonic Motor Functions in Humans and Animals

“…WMC for use in whole-gut transit was validated using dogs 109 and has been used in several studies in dogs, 110 , 111 , 112 pigs, 113 rabbits, 114 and horses. 115 To our knowledge, validated technologies have not been developed for use in small animals.…”

Review of Research Status and Development Trends of Wireless Passive LC Resonant Sensors for Harsh Environments

“…In 2014, Professor J.B. Wang proposed a new differential transduction circuit based on the LC mutual inductance detection mechanism for gastrointestinal pressure monitoring, which is composed of a sensor capsule and a detection unit. The micro-pressure system can realize long-term monitoring stability, and the sensitivity can reach up to 0.2491 kHz/kPa [ 34 , 35 , 36 ].…”