Shape-changing materials advance 3D printing

LCEs work by converting thermal energy – sourced from the sun, alternating currents, or other heat sources – into mechanical energy that can be stored and used on demand. This ability allows these materials to expand, contract, or reshape themselves, opening up possibilities, for example, in soft robotics, aerospace, and medicine.

Soft motors that work like muscles

LCEs are often referred to as "soft motors" because of their capacity to perform mechanical work in a way that are similar to traditional motors. However, unlike rigid motors, these soft materials can integrate with living tissues, and they could, for instance, be developed into implantable medical devices for targeted drug delivery, stents for minimally invasive procedures, or urethral implants to address incontinence.

How do they work?

The shape-shifting ability of LCEs depends on the alignment of their molecules. When the materials are exposed to external forces, such as magnetic fields or heat, their molecular structure undergoes controlled changes, which results in precise movements. Achieving this molecular alignment has traditionally required strong magnetic fields, up to two Tesla. However, researchers at OSU, and collaborators at Harvard, the University of Colorado, and national laboratories found a way to reduce the required field strength by almost 100 times using novel materials chemistry.

This breakthrough was made possible through a form of 3D printing called digital light processing (DLP). In this technique, a UV light hardens layers of liquid resin with high precision, creating complex shapes layer by layer. This method not only enables the creation of intricate LCE structures but also ensures that they can be programmed to respond to specific stimuli immediately after printing.

Applications beyond the lab

The potential applications for LCEs in robotics, for example, could enable the development of flexible robots capable of exploring hazardous environments, such as deep-sea or extraterrestrial terrains, where rigid robots struggle. In aerospace, they might act as actuators for automated systems like radar deployment or grappling mechanisms for space exploration.

Biomedical devices also stand to benefit. By mimicking natural tissue, LCEs can offer advanced solutions for implantable devices that adjust and adapt in response to changes in the body. For example, they could be used to create shape-memory materials that return to their original form after stress is removed, enabling reversible, repeated actuation.

A look to the future

OSU researchers are not only focused on the functional applications of LCEs but also on their mechanical properties. In related work, the team demonstrated how LCEs could be used to dissipate energy efficiently, such as in automotive shock absorbers or seismic dampers for buildings. This energy-damping capability, combined with the material’s flexibility, sets LCEs apart from other polymers.

One of the most intriguing aspects of this research is the ability to harness invisible forces – like magnetic fields or temperature gradients – to dramatically alter the material's behaviour.

The precision of the DLP printing process is another key factor – it achieves resolutions as fine as 15 microns. This precision enables the creation of small but intricate samples, approximately a few centimetres in size, which, though small, have the potential to make a big impact.

With support from the National Science Foundation and the Air Force Office of Scientific Research, OSU researchers are working to transform industries with their advancements in LCE technology.