‘Direct laser writing of liquid crystal elastomers oriented by a horizontal electric field’

Open Research Europe presents an interview with Marco Carlotti, a co-author of ‘Direct laser writing of liquid crystal elastomers oriented by a horizontal electric field’, in this month’s Research Spotlight. Read on to find out more about the research.

Can you share a summary of your Research Article?

Micro-actuators are small-scale active devices capable of generating mechanical motion of solids or fluids. In this study, we developed a new method for the printing of 3D micro-actuators that can change shape upon heating via direct laser writing (DLW) – a 3D microprinting technique, which makes use of two-photon polymerization to print 3D microstructures with high resolution and random complexity.

To obtain micro-actuators we used liquid crystal elastomers (LCEs), a class of stimuli-responsive polymeric materials that undergo reversible shape-change in response to environmental changes. Made up of bound liquid crystal molecules, LCEs form an extended network where they are aligned along a precise direction. This alignment, whilst fundamental for the working properties of the actuators, is not easy to achieve, especially in the case of DLW setups. By employing a system of flat and transparent electrodes directly on the printing substrates, we were able to apply a horizontal electric field which produced the desired alignment and was retained in the final microdevices.

What inspired you to investigate this?

During the last decade, Micro Electro-Mechanical Systems (MEMS) have played a major role in the paradigm shifts in technologies that influence our everyday lives. The continuous downsizing of electronic and mechanical components has resulted in an astonishing number of technological breakthroughs across several fields of applications such as the automotive industry, consumer electronics, and the healthcare sector among many. Despite these advancements, technologies suffer from drawbacks related to the materials and the printing techniques used, which makes the prototyping of new devices slow and costly. 

Direct laser writing (DLW) is an extremely versatile technique for the fabrication of diverse microsystems and gives absolute 3D-freedom that cannot be matched by common lithographic printing approaches. In addition, the possibility of using polymeric materials (while posing many limitations in terms of mechanical properties) offers the opportunity of including these functional materials in the fabrication of devices, where these polymeric materials can respond and adapt their properties to external stimuli. The micro-actuators presented in this study are an interesting example of this approach, being capable of a reliable motion when heated above 50°C. 

What were the outcomes of your research?

The horizontal electric field we applied demonstrated its usefulness in achieving a sufficient alignment of the liquid crystal matrix (and this alignment remains the same in the final printed structures). Using this technique, we discovered we could develop novel methodologies for the fabrication of working devices and micro-machines that can be fully 3D-printed even at the microscale. We also discovered that if a suitable electrode arrangement was designed, we could achieve several distinct alignment directions even on a single sample. This would allow for the preparation of functional micro-elements characterized by complex motions that could be integrated in 3D-printed MEMS.

Why is open research important to you and your co-authors?

On a global scale, the progress of science could benefit immensely from open data and information sharing at all levels. For our publication, we actively looked for journals that offered open access options that supported open data as well. We believe that open and reliable sharing of data and discussions can also foster collaborations and the development of networks in academia and research institutes, which can greatly benefit the career of young researchers.

What motivated you to publish with Open Research Europe?

We wanted to publish with Open Research Europe as the Platform offers a new and interesting take on peer review, in which the articles are made available right after minor feedback from the editors, and only then undergo the peer reviewing process. Moreover, the peer review process is open and available for everyone to browse. This approach offers two possible advantages: researchers can communicate their findings quickly, which in the case of some fields, can be of primary importance. Also, open peer review offers a realistic view on different insights that accompany the scientific debate concerning a specific subject which results in a more compelling way to evaluate the relevance of a new piece of research.

What are your next steps?

We are currently working on using smart materials and functional structures in the fabrication of Micro Electro-Mechanical Systems and other micro-machinery via direct laser writing (DLW) under the EU-funded project 5D NanoPrinting. To achieve our goal, we are working to expand the portfolio of functional materials that can be printed via DLW and possess properties such as high conductivity or tunable mechanical properties. With these tools, we aim to develop new approaches for the prototyping and fabrication of 3D-printed micro-devices and components that can be used in healthcare applications and consumer electronics. 

Want to find out more? Read the article here.