3D two-photon printing of hetero-microstructures by in-situ alignment of liquid-crystal elastomers

Münchinger, Alexander; Blasco, Eva; Hahn, Vincent; Beutel, Dominik; Woska, Simon; Monti, Joël; Rockstuhl, Carsten; Wegener, Martin

doi:10.1117/12.2578120

Cited by 4 publications

(5 citation statements)

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“…It is worth mentioning that the printing process in the presence of a bias, produced structures that do not replicate exactly the input design but appeared more compressed in the direction perpendicular to the director. While we do not know the origin of such discrepancy, a similar phenomenon was observed by Münchinger et al, 34 and could be related to the DLW printing process.…”

Section: Resultssupporting

confidence: 78%

“…Unlike what reported by Münchinger et al, 34 the actuation temperature was about 100 °C lower in our case (50 vs. 150 °C) despite the similar LC system employed. Notably, the temperature of actuation was comparable to that of cm-long films prepared from an identical formulation and under the same electric field (see ImageZ2 in Extended data 36 ).…”

Section: Resultscontrasting

confidence: 78%

“…One may overcome these issues by making use of electric fields to generate differently aligned phases within the same substrate: by placing electrodes accordingly, one may fabricate, in a single step, a series of actuators characterized by different properties and working conditions (even along their z-axis). Tartan et al investigated in several studies the behavior of DLW-printed LCE structures in presence of a vertical electric field 32,33 , however, to the best of our knowledge, only one other research group is currently studying the possibilities offered by arbitrary horizontal alignment by application of an electric field 34 . Compared to the former -and also in combination with it -, the latter approach offers more practical possibilities for the fabrication of MEMS, permitting the independent actuation of different parts in different directions.…”

Section: Introductionmentioning

confidence: 99%

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

Carlotti¹,

Tricinci²,

Hoed³

et al. 2021

Open Res Europe

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Background: The ability to fabricate components capable of performing actuation in a reliable and controlled manner is one of the main research topics in the field of microelectromechanical systems (MEMS). However, the development of these technologies can be limited in many cases by 2D lithographic techniques employed in the fabrication process. Direct Laser Writing (DLW), a 3D microprinting technique based on two-photon polymerization, can offer novel solutions to prepare, both rapidly and reliably, 3D nano- and microstructures of arbitrary complexity. In addition, the use of functional materials in the printing process can result in the fabrication of smart and responsive devices. Methods: In this study, we present a novel methodology for the printing of 3D actuating microelements comprising Liquid Crystal Elastomers (LCEs) obtained by DLW. The alignment of the mesogens was performed using a static electric field (1.7 V/µm) generated by indium-tin oxide (ITO) electrodes patterned directly on the printing substrates. Results: When exposed to a temperature higher than 50°C, the printed microstructures actuated rapidly and reversibly of about 8% in the direction perpendicular to the director. Conclusions: A novel methodology was developed that allows the printing of directional actuators comprising LCEs via DLW. To impart the necessary alignment of the mesogens, a static electric field was applied before the printing process by making use of flat ITO electrodes present on the printing substrates. The resulting microelements showed a reversible change in shape when heated higher than 50 °C.

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Section: Resultssupporting

confidence: 78%

Section: Resultscontrasting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Carlotti¹,

Tricinci²,

Hoed³

et al. 2021

Open Res Europe

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show abstract

“…Furthermore, such materials could be useful for those applications which require the devices to degrade to perform their function such as carriers for biomedical applications and in disposable electronics. In addition, these technologies could work synergistically with other functional resists fabrication of functioning MEMS devices intrinsically capable of responding to external stimuli, [ 14,15 ] sensing, [ 16 ] show enhanced properties, [ 17–19 ] controlled actuation, [ 20,21 ] and shape recovery. [ 22 ]…”

Section: Introductionmentioning

confidence: 99%

Novel, High‐Resolution, Subtractive Photoresist Formulations for 3D Direct Laser Writing Based on Cyclic Ketene Acetals

Carlotti

Tricinci

Mattoli

2022

Adv Materials Technologies

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Direct laser writing (DLW) is an innovative technology based on two‐photon polymerization processes which allow the 3D printing of architectures with arbitrary complexity at the (sub)micrometer scale. While most of the research interest in this field relies on additive manufacturing, subtractive approaches can be extremely helpful in nano/microfabrication, allowing the preparation of expendable scaffolds, replaceable parts, and for the protection of fragile structures. In this study, we show that the simple addition of 2‐methylene‐1,3‐dioxepane, a cyclic ketene acetal compound, to a series of different acrylate‐based photoresists results in functional formulations that allow the 3D‐printing of degradable poly(ester‐co‐acrylate) microstructures via DLW. These latter could be degraded reliably under mild conditions compatible with other photoresists and materials of common use in the fabrication of MEMS, thus opening new opportunities to design novel fabrication procedures. In addition, the possibility of using different acrylate mixtures without affecting the degradability, allows the users to choose between a broad range of properties for the printed structures to fit their needs, without affecting the degradability. Finally, the authors show the potential of these photoresists in the fabrication of shadowing masks on 3D objects and their selective degradation employing a photobase.

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“…[ 20,21 ] A key area in the continuing development of 2PP‐DLW is in the use of “smart” or functional resists, with growing interest in liquid crystalline (LC) materials. [ 22–25 ] We have previously demonstrated a polymerizable LC resist, where the properties of the final polymer material can be controlled during writing by the application of an electric field to change the molecular alignment. [ 26–28 ] In this paper, we demonstrate the fabrication of electrically switchable multi‐element DOEs that are encoded at different depths within the LC layer.…”

Section: Introductionmentioning

confidence: 99%

3D Switchable Diffractive Optical Elements Fabricated with Two‐Photon Polymerization

O'Neill

Salter

Zhao

et al. 2022

Advanced Optical Materials

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Direct laser writing is demonstrated by two‐photon polymerization of multi‐element diffractive optical components that can be switched on and off with an applied voltage. By exploiting the 3D capabilities of the laser microfabrication technique, multiple diffractive optical elements are written into a single liquid crystal (LC) layer. The switching behavior of the diffractive optical elements is controlled by simply changing the write‐voltage of the anisotropic polymer structures during fabrication. Initially, 2D diffraction gratings are written at different depths within the LC layer. Each element is then activated by applying a voltage of sufficient amplitude that causes the second diffractive optical element to become inactive. This is then followed by a demonstration of multi‐element computer generated holograms that are written at different depths within the LC layer. By altering the magnitude of the applied voltage, different images/patterns can be observed in the replay field using a simple electrode configuration. These compact and transmissive LC optical components could excel in applications where a degree of switchability is required but a highly pixelated fully programmable device is excessive.

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3D two-photon printing of hetero-microstructures by in-situ alignment of liquid-crystal elastomers

Cited by 4 publications

References 0 publications

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

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

Novel, High‐Resolution, Subtractive Photoresist Formulations for 3D Direct Laser Writing Based on Cyclic Ketene Acetals

3D Switchable Diffractive Optical Elements Fabricated with Two‐Photon Polymerization

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