Bioinspired Kirigami Capsule Robot for Minimally Invasive Gastrointestinal Biopsy

TL;DR

This paper introduces the Kiri-Capsule, a bioinspired, swallowable robot that can perform minimally invasive tissue biopsies in the gastrointestinal tract, addressing a key limitation of current capsule endoscopy.

Contribution

The Kiri-Capsule is the first kirigami-inspired capsule robot capable of controlled tissue penetration and biopsy, combining deployable sharp flaps with safe, repeatable operation.

Findings

Bench tests confirmed stable deployment angles of PI films.

Ex vivo studies showed effective tissue sampling comparable to standard forceps.

Biopsy forces were within safe ranges for GI tissue.

Abstract

Wireless capsule endoscopy (WCE) has transformed gastrointestinal (GI) diagnostics by enabling noninvasive visualization of the digestive tract, yet its diagnostic yield remains constrained by the absence of biopsy capability, as histological analysis is still the gold standard for confirming disease. Conventional biopsy using forceps, needles, or rotating blades is invasive, limited in reach, and carries risks of perforation or mucosal trauma, while fluid- or microbiota-sampling capsules cannot provide structured tissue for pathology, leaving a critical gap in swallowable biopsy solutions. Here we present the Kiri-Capsule, a kirigami-inspired capsule robot that integrates deployable PI-film flaps actuated by a compact dual-cam mechanism to achieve minimally invasive and repeatable tissue collection. The kirigami surface remains flat during locomotion but transforms into sharp protrusions upon cam-driven stretching, enabling controlled penetration followed by rotary scraping, with specimens retained in internal fan-shaped cavities. Bench tests confirmed that PI films exhibit a Young's modulus of approximately 20 MPa and stable deployment angles (about 34$^\circ$ at 15% strain), while ex vivo porcine studies demonstrated shallow penetration depths (median $\sim$0.61 mm, range 0.46--0.66 mm) and biopsy yields comparable to standard forceps (mean $\sim$10.9 mg for stomach and $\sim$18.9 mg for intestine), with forces within safe ranges reported for GI biopsy. These findings demonstrate that the Kiri-Capsule bridges passive imaging and functional biopsy, providing a swallowable, depth-controlled, and histology-ready solution that advances capsule-based diagnostics toward safe and effective clinical application.