Development and in Vivo Evaluation of an Intraluminal Bioelectronic Capsule for Gastrointestinal Neuromodulation

Introduction: Postoperative ileus (POI) is a common complication of abdominal surgery, characterized by temporary impairment of bowel motility that delays recovery and increases healthcare costs. In the United States, POI occurs in up to 25% of elective abdominal surgeries [1] and is estimated to account for $750 million to $1.46 billion in annual inpatient expenditures [2]. Current neuromodulation approaches such as gastrointestinal (GI) stimulators and vagus nerve stimulation (VNS) show potential but are impractical as they require invasive implantation and retrieval. Ingestible devices have been developed for monitoring or treatment of other GI diseases. This work introduces the intraluminal bioelectronic capsule (IBC) with the ability to monitor and electrically stimulate the intestinal lining to facilitate the motility recovery after POI. The IBC is designed to be naturally excreted, replacing the need for invasive implantation and explanation procedures.

Methods: The IBC incorporates a multi-modal sensing platform consisting of bio-impedance measurement, intraluminal pressure and temperature sensing, integrated within a biocompatible housing. Additionally, the device offers programmable burst biphasic electrical stimulation with a maximum current intensity of 10 mA, a pulse duration of 2 ms at frequencies up to 100 Hz, and a four-electrode configuration in which each electrode can be independently programmed. In vivo evaluation was conducted in four porcine with two assigned to the experimental group and two to the sham group. In each model, capsules were implanted in the jejunal and colonic intestines under isoflurane anesthesia. Postoperative ileus was induced by manual intestinal manipulation. The experimental group received electrical stimulation, while controls received none. Post-surgery, each model was administered 250cc barium contrast to qualitatively monitor the GI motility. X-ray imaging was performed on days 1, 2, and 3 following surgery (Figure 1). Two weeks post-surgery, tissue integrity, infection status, and healing was assessed via laparotomy.

Results: All implanted IBCs were naturally excreted without complications. Qualitative analysis of post-operative imaging indicated that the experimental group exhibited barium contrast progression to the cecum faster than the sham group, suggesting accelerated motility recovery compared to sham. Laparotomy revealed no evidence of mucosal injury, inflammation, or abnormal healing at the implantation sites.

Conclusion: These findings support the feasibility and safety of the IBC as a minimally invasive device for enhancing GI motility in POI. Its ability to both record and stimulate within the GI tract, combined with natural excretion, positions the IBC as a promising clinical tool.