Freestanding region-responsive bilayer for functional packaging of ingestible devices

Abstract

Ingestible capsules have the potential to become an attractive alternative to traditional means of treating and detecting gastrointestinal (GI) disease. As device complexity increases, so too does the demand for more effective capsule packaging technologies to elegantly target specific GI locations. While pH-responsive coatings have been traditionally used for the passive targeting of specific GI regions, their application is limited due to the geometric restrictions imposed by standard coating methods. Dip, pan, and spray coating methods only enable the protection of microscale unsupported openings against the harsh GI environment. However, some emerging technologies have millimeter-scale components for performing functions such as sensing and drug delivery. To this end, we present the freestanding region-responsive bilayer (FRRB), a packaging technology for ingestible capsules that can be readily applied for various functional ingestible capsule components. The bilayer is composed of rigid polyethylene glycol (PEG) under a flexible pH-responsive Eudragit® FL 30 D 55, which protects the contents of the capsule until it arrives in the targeted intestinal environment. The FRRB can be fabricated in a multitude of shapes that facilitate various functional packaging mechanisms, some of which are demonstrated here. In this paper, we characterize and validate the use of this technology in a simulated intestinal environment, confirming that the FRRB can be tuned for small intestinal release. We also show a case example where the FRRB is used to protect and expose a thermomechanical actuator for targeted drug delivery.

Miniaturized Capsule System Toward Real‐Time Electrochemical Detection of H2S in the Gastrointestinal Tract

“…Considerations for progressively updating the threshold value will be required, either by introducing a linear correction factor to account for sensor drift exceeding acceptable 5% deviation in current response, or by delaying when the measurement occurs using pH targeting to localize specific sections of the small bowel amenable to the sensor's operational lifetime. [ 95–97 ] Threshold triggered signaling was demonstrated by placing the packaged capsule into the gas testing chamber and repeatedly modulating the H 2 S concentration between 0 and 3.6 ppm following saturation. Figure 5D shows the corresponding amperogram summarizing this implementation of the threshold value.…”