Bioinspired Kirigami Capsule Robot for Minimally Invasive Gastrointestinal Biopsy
Raymond Shing-Yan Tang, and Hongliang Ren,∗
AI summary
Problem
Wireless capsule endoscopy lacks tissue acquisition capability, while existing capsule biopsy solutions are invasive, carry perforation risks, or fail to provide structured tissue for pathology.
Approach
The Kiri-Capsule uses a compact dual-cam mechanism to stretch kirigami-patterned polyimide flaps, transforming them from flat to sharp protrusions that scrape and retain mucosal tissue in internal cavities.
Key results
- Dual-cam actuation enables repeatable, depth-controlled kirigami flap deployment (~34° at 15% strain)
- Ex vivo porcine testing achieves shallow penetration (~0.61 mm) with safe interaction forces
- Biopsy yields match standard forceps (~10.9 mg stomach, ~18.9 mg intestine)
- Compact 17×22 mm prototype maintains swallowable dimensions while integrating tissue capture cavities
Why it matters
Enables safe, swallowable tissue acquisition for GI diagnostics, bridging the gap between passive imaging and definitive histological analysis.
Abstract
Wireless capsule endoscopy (WCE) has trans- formed gastrointestinal (GI) diagnostics by enabling noninva- sive 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 perfo- ration 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 inte- grates 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◦at 15% strain), while ex vivo porcine studies demonstrated shallow penetration depths (median ∼0.61 mm, range 0.46–0.66 mm) and biopsy yields comparable to standard forceps (mean ∼10.9 mg for stomach and ∼18.9 mg for small 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.