3DFold - Programmed folding of mesoscopic 3D objects by viscoelastic reconfiguration

• Applicant: Dr.-Ing. Robert Kirchner
• Subject Area: Microsystems ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 412265813

Current techniques for the production of real 3D structures, which might contain undercuts and hidden structures, are either limited in their resolution or do not achieve a sufficient production speed for high volume production. In addition, the existing techniques are hardly scalable and cannot be used in an equivalent way for structural dimensions in the range from a few hundred nanometers up to a few hundred micrometers. However, there are applications which require a high resolution method, can be used across scales and are capable of high volume production. Such demanding applications include sensors based on 3D plasmonic particles, the generation of intelligent and uniquely identifiable 3D particles for digital microfluidics, 3D actuators for micro- and nano-softrobotics, capture-release applications, 3D micro- and nanoelectronic systems as well as multiplex methods in bio and gene analysis using 3D particles for suspension array techniques. The aim of this application is to establish a new technology and to demonstrate its usability by means of two selected demonstrator applications from the field of particle transport and plasmonics. This proposal uses so-called origami structure generation, i. e., the self-folding of 3-dimensional objects emanating from a planar 2-dimensional structure according to a given sequence and triggered by an external stimulus. The innovation of this application lies in the use of thermoplastic actuators to drive this folding as well as the technologically efficient modification and programming of the activation temperature of the polymer actuators. By a thermal stimulus slightly exceeding the glass transition temperature, capillary forces are generated by the actuators, which transform planar structures by out-of-plane rotations into 3D objects. The advantages of the method proposed here are the controllability and the programmability of the softening of the thermoplastic materials, the usability across scales as well as the large material diversity for the 3D objects from polymers to semiconductors and metals to magnetic materials. During the structural transformation or reconfiguration, for example, particles can be trapped. Furthermore, the 3D objects can be provided with an identification code on a plasmonic basis and are thus clearly recognizable as individual particles. Both scenarios will be demonstrated within this proposal.

• DFG Programme: Research Grants