Fig. 5: Ultrasound-based leak detection ex vivo and in vivo.

Ex vivo ultrasound images obtained using an ipad controlled Clarius L7 HD probe of (a) a TurnOFF patterned hydrogel patch attached to intestine filled with SIF, equipped with a 4 mm hole simulating the perforation. The suture sites are monitored over six hours, showcasing pattern disappearance, N ≥ 3. b TurnON sensing element equipped hydrogel patch attached to an intestinal tissue model, filled with SGF indicating suture perforation by increased ultrasound scattering after fifteen minutes of contact with SGF, n ≥ 3. c In vivo application of TurnOFF DL-patches on piglet intestine with a defect. c-i 4 mm defect formation on live small porcine intestine. c-ii photograph of patch immediately after application on the defect. Sensing elements are clearly visible (red arrows). c-iii sealant patch 2 h post application on formed defect, presenting containment of digestive leak. d Ultrasound data recorded (d-i) immediately after patch application and surgical closure of the abdomen with a running suture. Sensing elements are discernible (red arrows). (ii), (d-ii) 2 h after application, sensing elements were not detectable anymore, in line with the disappearance of the opaque dots (c-iii). e Histological micrographs of intestinal tissue collected after euthanasia of the piglet shows firm attachment of the hydrogel to the serosa of the small intestine tissue and no visible tissue damage. Two samples were analysed yielding visually indistinguishable results. Figure wide color coding: red arrows—TurnOFF sensing element active. Figure 5d has been created using biorender.com.