Humidity-responsive actuation of programmable hydrogel microstructures based on 3D printing

Lv, Chao; Sun, Xiang‐Chao; Xia, Hong; Yu, Yan-Hao; Gong, Wenjie; Cao, Xiaoyuan; Li, Shun‐Xin; Wang, Yingshuai; Chen, Qi‐Dai; Yu, Yude; Sun, Hong‐Bo

doi:10.1016/j.snb.2017.12.053

Cited by 106 publications

(55 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Solvent‐induced swelling of a network can also be used for actuation, although it is very system‐environment specific. Examples of such actuators are very common: Lv et al used high‐ M w PEG‐DA to obtain structures with programmable swelling as a function of the crosslink ( Figure a–d); Tian et al used butylmethacrylate and propoxylated trimethylolpropane triacrylate to print a micromachine that was able to move a load; Xiong et al obtained a working micropump which relied on the asymmetric swelling of an acrylamide, 2‐acrylamido‐2‐methylpropane sulfonic acid, and N , N ′‐methylenebis(acrylamide) membrane; by combining high‐ M w PEG‐DA and 2‐carboxyethyl acrylate, Scarpa and co‐workers prepared simple architectures that could respond to changes in pH and ionic strength . The drawback of these systems is that all the processes are diffusion controlled and thus slow (unless thin structures are built).…”

Section: Homogeneous Materialsmentioning

confidence: 99%

Functional Materials for Two‐Photon Polymerization in Microfabrication

Carlotti

Mattoli

2019

Small

161

126

View full text Add to dashboard Cite

The creation of 3D micro and nanostructures is of particular interest in the fields of photonics, [3] microelectromechanical systems (MEMS), [4] metamaterials, [5] micro/ nanofluidics, [6] cellular proliferation, and differentiation. [7] To create 3D objects of arbitrary shape, 3D printing techniques offer many versatile solutions. [8] Among these, direct laser writing (DLW) allows for the simple preparation of (sub)micrometric objects and patterns with a resolution that can go below 100 nm. [9][10][11] DLW is an additive manufacturing technique based on twophoton polymerization (2PP). To produce a structure, a fs-pulsed long-wavelength laser is focused, by means of optical elements, in a photosensitive resin which is able to crosslink (negative photoresist) or decompose (positive photoresist) under an energetic radiation but that is also transparent at the laser wavelength: if the intensity of the excitation radiation is high enough-as it is the case in the focus-the resin can undergo two (or more)-photon absorption and polymerize (or decompose). [12] Such multiphotons absorption phenomena are nonlinear and the cross-section of the different materials scales with the square (or higher) of the intensity of the radiation. For these reasons, the laser beam can enter the photoresist without being absorbed and trigger the photochemical process(es) only in a small volume around the focus. This volume is named "voxel" being the 3D analogue of a 2D pixel. [13] The absorption probability outside of the voxel is small, thus suppressing the propagation of the reaction and resulting in fine resolution. By moving around the voxel, one can obtain complex 3D structures that can be isolated after developing. [14,15] More than two decades have passed since DLW was proposed [16] and much progress has been made in terms of improving feature size and resolution, [9,[17][18][19][20][21] enlarging the library of materials that can be used, [22][23][24][25] and the possible applications of these finely controlled structures. [6,[25][26][27][28] The research on functional materials-here intended as materials that can be employed in 2PP and show peculiar features that encourage their use in particular applications-has propelled the field of micro/nanostructuring forward by promoting the interdisciplinarity between chemistry, physics, biology, and material science. [26] In this review, we will summarize and critically discuss the different functional materials proposed in the literature, dividing them and confronting them according to their preparation and their application (Figure 1; Table 1). We start the main body discussing the properties and applications of nanocomposite resists used in 2PP. In the second part, Direct laser writing methods based on two-photon polymerization (2PP) are powerful tools for the on-demand printing of precise and complex 3D architectures at the micro and nanometer scale. While much progress was made to increase the resolution and the feature size throughout the years, by carefully designing a material, one...

show abstract

Section: Homogeneous Materialsmentioning

confidence: 99%

Functional Materials for Two‐Photon Polymerization in Microfabrication

Carlotti

Mattoli

2019

Small

161

126

View full text Add to dashboard Cite

show abstract

“…S. lepidophylla has provided the opportunity to study three-dimensional gradients at small length scales that lead to macro-level actuation. The cell wall properties identified here could be explored further with computational models to extract features for the development of synthetic actuators with improved performance and structure at the micro-level 2,3 .…”

Section: Discussionmentioning

confidence: 99%

“…Current biomimetic research involves a multi-scale approach to investigate how structural and mechanical properties at various length-scales determine organism function 2 . As more hierarchical models are studied, and their micro-and nanoscale properties better understood, more complex biomimetic and actuating devices can be designed 2,3 . Of the many organisms studied, plants are particularly interesting because of the wide range of functions and structures produced from a limited set of constituent materials, i.e.…”

mentioning

confidence: 99%

Nano-indentation reveals a potential role for gradients of cell wall stiffness in directional movement of the resurrection plant Selaginella lepidophylla

Asgari

Brulé

Western

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Stiffness, defined as the ability of a material to resist deformation in response to an applied stress, determines the direction and extent of conformational changes undertaken by a material and hence is a critical mechanical property governing actuation response. The stiffer a material is, the less it deforms under a mechanical load. By layering or otherwise locally joining materials with dissimilar stiffness in a composite material, it is possible to control the global deformation in a specific direction 14,15. Stiffness profiles leading to deformation in S. lepidophylla have been studied at the organ and tissue level 10,11. Here, we present a complementary nanoscale investigation that sheds light on previously unexplored factors controlling the stiffness of S. lepidophylla in static and time-varying loads. The specific focus is on the elastic moduli of cortical cell walls, and the aim is to understand their contribution to the observed direction and degree of curling of inner stems. We take advantage of atomic force microscopy (AFM), a technique frequently used to study plant cell wall mechanics 16-18. In particular, we use AFM indentation to locally measure the nanoscale elastic properties of cell walls, as well as to assess the level of inhomogeneity and stiffness gradients of the tissue across representative transverse sections of the plant, both longitudinally (stem tip to base) and between adaxial and abaxial stem sides. We also preliminarily investigate the viscoelastic behaviour at given loading rates. Materials and Methods Plant materials. Mature S. lepidophylla plants were purchased from Canadian Air Plants (New Brunswick, Canada), and maintained in a desiccated state at 25 °C and ~30-50% relative humidity until use. Prior to experimentation, S. lepidophylla plants were placed in a plate of water and allowed to rehydrate for three consecutive days to achieve 100% relative water content. Time-lapse video capture. Video capture was adapted from the protocol in Rafsanjani et al. 10. Time-lapse videos were captured using a Logitech C920 HD Pro Webcam (1080p, Carl Zeiss optics) and Video Velocity Time-Lapse Studio software (Candylabs). S. lepidophylla plants were allowed to rehydrate for 24 hours. Individual inner stems were cut from the plant at the root-stem interface and secured in a metal clamp, which was affixed to the base of a square Petri dish. Stems were then allowed to air-dry for approximately 6 hours, during which time changes in their curvature were captured via time-lapse filming at frame rate of 1 min 21 s. Stems were taken from four different S. lepidophylla plants. In total, four inner stems were tested and displayed similar curling/uncurling patterns.

show abstract

“…Three-dimensional printing has high potential in the future for the production of hydrogel sensors and actuators, as concluded from the above points, as there are constant improvements being made to produce very soft hydrogels. For example, researchers performed a study on the humidity-driven actuation of hydrogels produced by 3D printing in a two-photon polymerization where the humidity-driven swelling was controlled by adjusting the cross-linking density of voxels in the microstructure [322]. In another study, the 3D printing of soft actuators was performed for numerous external stimuli and controls, producing customized actuators for real-life applications [142].…”

Section: Rapid Prototyping Tools: Hydrogel-based 3d Printing For Bmentioning

confidence: 99%

Hydrogel Actuators and Sensors for Biomedical Soft Robots: Brief Overview with Impending Challenges

2018

View full text Add to dashboard Cite

There are numerous developments taking place in the field of biorobotics, and one such recent breakthrough is the implementation of soft robots-a pathway to mimic nature's organic parts for research purposes and in minimally invasive surgeries as a result of their shape-morphing and adaptable features. Hydrogels (biocompatible, biodegradable materials that are used in designing soft robots and sensor integration), have come into demand because of their beneficial properties, such as high water content, flexibility, and multi-faceted advantages particularly in targeted drug delivery, surgery and biorobotics. We illustrate in this review article the different types of biomedical sensors and actuators for which a hydrogel acts as an active primary material, and we elucidate their limitations and the future scope of this material in the nexus of similar biomedical avenues.

show abstract

Humidity-responsive actuation of programmable hydrogel microstructures based on 3D printing

Cited by 106 publications

References 45 publications

Functional Materials for Two‐Photon Polymerization in Microfabrication

Functional Materials for Two‐Photon Polymerization in Microfabrication

Nano-indentation reveals a potential role for gradients of cell wall stiffness in directional movement of the resurrection plant Selaginella lepidophylla

Hydrogel Actuators and Sensors for Biomedical Soft Robots: Brief Overview with Impending Challenges

Contact Info

Product

Resources

About