Luke A Beardslee, PhD, MD, George E Banis, Justin M Stine, Rajendra Mayavan Sathyam, Reza Ghodssi, PhD. University of Maryland
Objective of the technology or device: We report an ingestible capsule for pH-targeted sampling and sensing within the human gut. Current methods for evaluating gastrointestinal (GI) health entail imaging or endoscopic sampling. Repeated procedures can be cumbersome to patients and costly to the healthcare system, especially when they require sedation. There are substantial potential benefits from the development and adoption of compact swallowable sensing systems capable of early disease detection, which do not require sedation or expensive imaging equipment. To this end, we investigate a Bluetooth enabled capacitive sensing capsule system which utilizes pancreatic lipase sensors.
Description of the technology and method of its use or application: In the present study, microfabricated interdigitated capacitive sensors are coated with a thin film of triglyceride, which is digested by pancreatic lipase changing the dielectric permittivity over the sensors. The measurements in lipase-containing solutions are compared to buffer alone. The sensor readout is designed on a custom circuit board containing a capacitive sensor interface, which connects to a Bluetooth microcontroller and appropriate power electronics. The system is powered from a compact lithium polymer battery and all of the components are inserted into a 3D-printed biocompatible capsule with a sensing chamber accessible to the external environment via embedded inlets. The system is paired with a nearby mobile phone using Bluetooth and enters low-power mode until triggered to initiate sensing. Embedded microfluidic inlets on the 3D-printed capsule are coated with Eudragit L100 to allow analyte to reach the sensor based on the pH of the solution surrounding the capsule. For testing, the capsule is inserted into either acidic (negative control) or neutral solutions. For the experimental case, 1 mM pancreatic lipase is introduced into the system. Capacitance measurements are transmitted in real time to a mobile app, saved with each sample, and later transmitted to a computer for analysis via MATLAB. In addition, the ability of the Bluetooth link to transmit through simulated tissue was tested using ground pork.
Preliminary Results: The sensors measured ~600% difference in capacitance increase as an indicator that sampling had been achieved via fluid inflow to the sensing chamber after 15 min within neutral pH, versus the acidic pH where the coating continued to seal the inlets over the >1 hour insertion period. The sensors measured another ~250% increase in capacitance and 31.2% decrease in film thickness in response to lipase-spiked solution compared to a decrease of ~6% and ~3.1% respectively, for neutral buffer only. Furthermore, the Bluetooth signal could be transmitted through at least 75 mm of ground pork without breaking the connection, with a packet loss of ~-93.3dBm.
Conclusions/Future Directions: We demonstrate a capsule utilizing hybrid packaging and digestible materials for pH-targeted sampling and sensing of pancreatic lipase. The sensors will be tested with lower concentrations of lipase and with media containing other pancreatic enzymes such as trypsin and amylase. Future work will also focus on exposing the capsule to relevant environmental conditions such as simulated peristalsis. Ultimately the capsule is intended for cost-effective screening for pancreatic pathologies.
Presented at the SAGES 2019 Annual Meeting in Baltimore, MD.
Abstract ID: 98702
Program Number: ETP727
Presentation Session: Emerging Technology Poster Session (Non CME)
Presentation Type: Poster