Seung Yun Yang^1,2,3, Eoin D. O’Cearbhaill^1,2,3, Geoffroy C. Sisk⁴, Kyeng Min Park⁵, Woo Kyung Cho^1,3, Martin Villiger⁶, Brett E. Bouma^3,6, Bohdan Pomahac⁴ & Jeffrey M. Karp^1,2,3

¹ Division of Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. ² Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, Massachusetts 02138, USA. ³ Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. ⁴ Department of Surgery, Division of Plastic Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, Massachusetts 02115, USA. ⁵ Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138, USA. ⁶Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA.

Correspondence to: Jeffrey M. Karp

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here inspired by the endoparasite Pomphorhynchus laevis, which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~3.5-fold increase in adhesion strength compared with staples in skin graft fixation, and removal force of ~4.5 Ncm^-2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics.