They create a "living" that could emulate the heartbeat

In an internationally pioneering new line of research combining fusion electrowriting of smart materials for biomedical applications and soft robotics, scientists have for the first time used stimulus-sensitive active materials, leading to active biomimetic structures with mechanical functions that can be digitally programmed. This advance could be the basis for making cell cultures that more accurately emulate living tissue.

The work has been carried out by the team led by Carlos Sánchez Somolinos, from the Aragon Institute of Nanoscience and Materials (INMA), a joint institute of the Higher Council for Scientific Research (CSIC) and the University of Zaragoza, in Spain.

“Manufactured with suitable materials, these structures could serve as mechanically active biomimetic scaffolds, as opposed to the passive ones currently used, providing, under adequate stimulation, a scaffold on which the cells grown on it feel the cyclical forces they experience in cells. living tissues, for example, the heart”, explains Sánchez Somolinos. They sign the study together with INMA researcher Mehrzad Javadzadeh, a doctoral student at the University of Zaragoza at INMA, and Jesús del Barrio, professor at the University of Zaragoza and researcher at INMA.

This novel microfabrication platform is applied for the first time in the world to liquid crystal elastomers, intelligent materials that mechanically respond to an external stimulus (in this case, temperature). The presented methodology has made it possible to digitally deposit ultrafine liquid crystal elastomer fibers with diameters of just a few microns, compared to those of hundreds of microns typically obtained by conventional 3D printing.

As a result, microstructures of these materials with very small dimensions have been obtained that until now were inaccessible with other structuring techniques. The proposed new technique thus surpasses current methodologies for microfabrication of these materials in regards to their size and control of molecular orientation, making it possible to obtain unprecedented intelligent microstructures with mechanical deformation on demand. “This work gives us the opportunity to explore the small,” sums up Sánchez Somolinos.

During the electrowriting process, the material acquires a preferred microscopic orientation that is key to precisely controlling the magnitude and direction of the forces that the material then exerts when it is excited with temperature. The structures prepared with this new printing platform have an intelligent character, deforming in a controlled manner in the face of external stimuli, and possess a remarkable capacity to carry out efforts and mechanical work that is potentially useful in fields such as soft robotics and biomedicine.

Detail of the microstructure created by the researchers. (Image: CSIC / INMA)

Currently, the electrowriting technique is used by some international research groups in the field of biomedicine in combination with passive biocompatible materials, such as polycaprolactone, to prepare static scaffolds for cell culture that mimic the structural characteristics found in native living tissues. like the myocardium.

The electrowriting microstructuring of stimulus-sensitive active materials, demonstrated in the present work, leads to active biomimetic structures with digitally programmed mechanical functions. “The aim is to find structures that emulate the extracellular matrix in the most representative way possible, that is, three-dimensional and dynamic”, explains the researcher.

The study is titled “Melt electrowriting of liquid crystal elastomer scaffolds with programmed mechanical response”. And it has been published in the academic journal Advanced Materials.

This research strengthens the already outstanding position of the CSIC in the field of liquid crystal elastomers for soft robotics at an international level. Already in 2017, the INMA Advanced Manufacturing Laboratory, led by Sánchez Somolinos, demonstrated for the first time the 4D printing of these materials, a technique that allows extruding and depositing fibers of the order of hundreds of microns to manufacture intelligent structures with materials of liquid crystal elastomer. This work was the seed of two European projects coordinated by the CSIC, Prime and Storm-Bots.

In this sense, Sánchez Somolinos is also coordinator of both. On the one hand, Storm-Bots aims to train 13 young researchers in the area of ​​materials for soft robotics. The incorporation of intelligent materials, which respond with a significant change in one of their physical properties in response to an external stimulus (such as heat, light, or an electric or magnetic field), constitutes an opportunity in robotics to develop new elements and devices. disruptive soft robotics and can open up new possibilities in terms of designs, functions and responses, inaccessible to conventional hard robots. Developments in this area are expected to revolutionize the fields of minimally invasive surgery, material handling, electronic skin, and human-machine interfaces.

On the other hand, Prime pursues the implementation of microfluidic devices, chips with microchannels through which fluids can circulate controlled by these intelligent materials that are deposited by 4D printing. PRIME seeks to demonstrate the feasibility of this technology that could allow chemical analysis of fluids in a fast, cheap and portable way. Its potential applications would include clinical analysis, water analysis or veterinary diagnostics. (Source: CSIC)