Paper cuts are a common injury that can cause significant pain and discomfort [1]. Surprisingly, the physics underpinning a thin flexible sheet of paper slicing into soft tissues remains unresolved. (Other cases, such as chess-wire cutters, have been described; e.g., [2].) In particular, the unpredictable occurrence of paper cuts, often restricted to a limited thickness range, has not been explained. Here, we visualized and quantified the motion, deformation, and stresses during paper cuts, uncovering a remarkably complex relationship between cutting, geometry, and material properties [3]. A model based on the hypothesis that competition between slicing and buckling controls the probability of initiating a paper cut was developed and successfully validated.
Our experiments revealed that competition between slicing and buckling underlies the erratic nature of paper cuts. Thin paper can’t cut because it lacks the structural integrity to resist buckling. Thick paper, in contrast, distributes the load across a large area and is also unable to cut. This explains why only paper within a narrow thickness range can cut. The most hazardous paper thickens is 65 μm, corresponding, e.g., to dot matrix paper or printed scientific journals (including Nature and Science).
Finally, we developed the Papermachete, a cost-effective paper-based scalpel based on our results. It uses scrap paper blades and can easily cut into vegetables and meat. To 3D print your own, use the files accessible here.
October 10th 2024: Spektrum.de
October 7th 2024: Chemical and Engineering News
September 13th 2024: Youtube, Videnskab.dk
September 10th 2024: ZDF (Facebook)
September 7th 2024: Science Alert
September 7th 2024: Donga Science
September 6th 2024: Weekendavisen
September 4th 2024: Radio SRF 1, Kultur aktuell
September 1st 2024: Physics World
August 29th 2024: GEO Magazine
August 28th 2024: Nature Briefings (Podcast)
August 27th 2024: Popular Science
August 23rd 2024: Nature, Research Highlights
August 12th 2024: ABC Melbourne, Drive
August 7th 2024: Videnskab.dk (Youtube, September 13th 2024)
August 6th 2024: The Morning Show
August 3rd 2024: New York Post
August 2nd 2024: This Is Going Well, I Think with David Cooper
July 22nd 2024: Economy Chosun
July 19th 2024: Huffington Post, Korea
July 9th 2024: Hankyoreh Newsletter
Jun 28th 2024: CBC Radio, As It Happens
Table I (Caption): "MPa" -> "GPa" (27 Aug 2024)
Kaare H. Jensen, Department of Physics, Technical University of Denmark Email: khjensen@fysik.dtu.dk Phone: +45 2231 5241
Please access the preprint, images, and videos here.
- [1] Mirsky, S., The unkindest cut, Scientific American 306, 80, 2012
- [2] Reyssat, E., Tallinen, T., Le Merrer, M., & Mahadevan, L. Slicing softly with shear. Physical review letters, 109(24), 244301, 2012
- [3] Arnbjerg-Nielsen S. F., Biviano M. D., & Jensen, K. H., Competition between slicing and buckling underlies the erratic nature of paper cuts, Physical Review E (2024) accepted preprint journal.
We are grateful to Norwid Behrnd and Keunhwan Park for providing additional examples of press coverage.
