# Rapid Design and Fabrication of Body Conformable Surfaces with Kirigami Cutting and Machine Learning

## TL;DR

This paper introduces a fast and low-cost method to create body-conformable wearable devices using kirigami cutting and machine learning, tailored to the knee joint.

## Contribution

The novel integration of kirigami cutting with machine learning enables rapid, personalized fabrication of conformable wearables.

## Key findings

- A machine learning model using Gaussian Process regression accurately predicts kirigami deformation with an R2 score of 0.996.
- The pipeline successfully conforms to over 75% of the skin area across three subjects using rapid laser cutting.
- The method balances conformability performance and cost for personalizing wearables.

## Abstract

By integrating the principles of kirigami cutting and data‐driven modeling, this study aims to develop a personalized, rapid, and low‐cost design and fabrication pipeline for creating body‐conformable surfaces around the knee joint. The process begins with 3D scanning of the anterior knee surface of human subjects, followed by extracting the corresponding skin deformation between two joint angles in terms of longitudinal strain and Poisson's ratio. In parallel, a machine learning model is constructed using extensive simulation data from experimentally calibrated finite element analysis. This model employs Gaussian Process (GP) regression to relate kirigami cut lengths to the resulting longitudinal strain and Poisson's ratio. With an R2 score of 0.996, GP regression outperforms other models in predicting kirigami's large deformations. Finally, an inverse design approach based on the Covariance Matrix Adaptation Evolution Strategy (CMA‐ES) is used to generate kirigami patch designs that replicate the in‐plane skin deformation observed from the knee scans. This pipeline was applied to three human subjects, and the resulting kirigami knee patches were fabricated using rapid laser cutting, requiring less than a business day from knee scanning to kirigami patch delivery. The low‐cost, personalized kirigami patches successfully conformed to over 75% of the skin area across all subjects. The kirigami‐inspired, machine‐learning‐driven design and fabrication pipeline presents a balanced trade‐off between conformability performance and cost for personalizing wearables, thus establishing a foundation for a wide range of new functional devices.

By integrating the principles of kirigami cutting and data‐driven modeling, this study aims to develop a personalized, rapid, and low‐cost design and fabrication pipeline for creating body‐conformable surfaces around the knee joint. This pipeline presents a balanced trade‐off between conformability performance and cost for personalizing wearables, thus establishing a foundation for a wide range of new functional devices.