Multiple Shape Transformations of Composite Hydrogel Sheets

Abstract

Soft materials undergoing shape transformations in response to changes in ambient environment have potential applications in tissue engineering, robotics and biosensing. Generally, stimulus-responsive materials acquire two stable shapes corresponding to the "on" and "off" states of the external trigger. Here, we report a simple, yet versatile approach to induce multiple shape transformations of a planar hydrogel sheet, each triggered by a particular, well-defined external stimulus. The approach is based on the integration of small-scale multiple polymer components with distinct compositions in the composite gel sheet. In response to different stimuli, the structural components undergo differential swelling or shrinkage, which creates internal stresses within the composite hydrogel sheet and transforms its shape in a specific manner.

Ultrafast Digital Printing toward 4D Shape Changing Materials

“…We note that processes that rely on physical masks to spatio-selectively define swellability in polymer films have been reported before. [21][22][23] However, physical masking methods cannot be used to create digitally defined arbitrary shapes. More importantly, they typically can only control light exposure in a non-continuous on and off manner.…”

Light switchable optical materials from azobenzene crosslinked poly(N-isopropylacrylamide)-based microgels

“…This interesting behavior has revolutionized the way we think about drug delivery, and has led to many advances in various elds of material science, chemistry, engineering, and physics. 2,5,6 Of the various stimuli that can be used to excite these systems, light has attracted much interest due to its ability to locally excite materials from remote locations. 7,8 Additionally, light induced excitation of materials can easily be started/stopped by simply switching the excitation source on/off, while the magnitude of the response can be tuned by modulating the excitation source intensity, and/or wavelength.…”

Quantifying the bending of bilayer temperature-sensitive hydrogels

“…With a change in the temperature, these hydrogels can undergo a phase transition, upon which their volume can discontinuously change by up to 1000 times [23]. For the application of temperature-responsive hydrogels [24][25][26][27][28][29], both good responsive properties and good mechanical properties are necessary to generate desirable forces or deformations.…”