A CHEMO-MECHATRONIC ORIGAMI DEVICE FOR CHEMICAL SENSING Chang Liu Expeditionary Robotics Lab Mechanical and Industrial Engineering Northeastern University Boston, Massachusetts 02115 Email: liu.chang7@husky.neu.edu Conor M. Gomes Biomaterials Design Group Chemistry and Chemical Biology Northeastern University Boston, Massachusetts 02115 Email: gomes.co@husky.neu.edu Kevin J. McDonald Expeditionary Robotics Lab Mechanical and Industrial Engineering Northeastern University Boston, Massachusetts 02115 Email: mcdonald.kev@husky.neu.edu Leila F. Deravi Biomaterials Design Group Chemistry and Chemical Biology Northeastern University Boston, Massachusetts 02115 Email: l.deravi@northeastern.edu Samuel M. Felton ∗ Expeditionary Robotics Lab Mechanical and Industrial Engineering Northeastern University Boston, Massachusetts 02115 Email: s.felton@northeastern.edu ABSTRACT This paper presents the design, fabrication, and operation of a chemo-mechatronic system that changes its geometry and elec- trical functionality in the presence of specific chemical signals. To accomplish this, we integrated a protein hydrogel with an alu- minum substrate and flexible circuit in a low-profile laminate. To demonstrate the concept, we have built and tested a sensor that lights an LED when actuated in the presence of polyethylene gly- col (PEG). NOMENCLATURE PEG Polyethylene Glycol PDA Polydopamine INTRODUCTION Self-folding is a process in which a flat sheet folds itself along pre-programmed hinges to form a three-dimensional struc- ture. It has been applied to a variety of devices, from meter- ∗ Address all correspondence to this author. scale robots [1] to micrometer-scale cell-biopsy grippers [2]. It can be used to automate the assembly of multiple machines in parallel [3], construct devices that are too small to manipulate manually [4], and transform machines between different shapes for different locomotion modes [5] [6]. Folding can be actuated with a variety of techniques, including shape memory polymers [7] [8], shape memory alloys [9–13], and pneumatics [14] [15]. One particular type of self-folding uses hydrogel swelling [16]. Hydrogels have a wide range of uses due to their swelling behavior, including biomedical sensors and mechanical parts [17–19]. They can be actuated by thermal reaction [20] or by successive extension of cross-links [21]. Many hydrogels are also bio-compatible and can be used to deliver drugs and other molecules [22]. In this paper we use gelatin [23] from denatured collagen to form a hydrogel [24] [25]. In this paper we present a self-folding sensor that combines an active hydrogel layer with an aluminum scaffold and a cop- per circuit. The general concept of operation is that a chemical reaction in the hydrogel causes mechanical deformation of the scaffold, which in turn leads to electrical changes in the circuit that can be used to sense the original chemical signal. We first 1 Copyright © 2018 ASME Proceedings of the ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems SMASIS2018 September 10-12, 2018, San Antonio, TX, USA SMASIS2018-8005 Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 11/20/2018 Terms of Use: http://www.asme.org/about-asme/terms-of-use