Hydrogels are important functional materials useful for 3D cell culture, tissue engineering, 3D printing, drug delivery, sensors, or soft robotics. The ability to shape hydrogels into defined 3D structures, patterns, or particles is crucial for biomedical applications. Here, the rapid photodegradability of commonly used polymethacrylate hydrogels is demonstrated without the need to incorporate additional photolabile functionalities. Hydrogel degradation depths are quantified with respect to the irradiation time, light intensity, and chemical composition. It can be shown that these parameters can be utilized to control the photodegradation behavior of polymethacrylate hydrogels. The photodegradation kinetics, the change in mechanical properties of polymethacrylate hydrogels upon UV irradiation, as well as the photodegradation products are investigated. This approach is then exploited for microstructuring and patterning of hydrogels including hydrogel gradients as well as for the formation of hydrogel particles and hydrogel arrays of well‐defined shapes. Cell repellent but biocompatible hydrogel microwells are fabricated using this method and used to form arrays of cell spheroids. As this method is based on readily available and commonly used methacrylates and can be conducted using cheap UV light sources, it has vast potential to be applied by laboratories with various backgrounds and for diverse applications.
Light-powered soft steam engines for self-adaptive oscillation and biomimetic swimming
Oscillation plays a vital role in the survival of living organisms in changing environments, and its relevant research has inspired many biomimetic approaches to soft autonomous robotics. However, it remains challenging to create mechanical oscillation that can work under constant energy input and actively adjust the oscillation mode. Here, a steam-driven photothermal oscillator operating under constant light irradiation has been developed to perform continuous or pulsed, damped harmonic mechanical oscillations. The key component of the oscillator comprises a hydrogel containing Fe 3 O 4 /Cu hybrid nanorods, which can convert light into heat and generate steam bubbles. Controllable perturbation to the thermomechanical equilibrium of the oscillator can thus be achieved, leading to either continuous or pulsed oscillation depending on the light intensity. Resembling the conventional heat steam engine, this environment-dictated multimodal oscillator uses steam as the working fluid, enabling the design of self-adaptive soft robots that can actively adjust their body functions and working modes in response to environmental changes. An untethered biomimetic neuston-like robot is further developed based on this soft steam engine, which can adapt its locomotion mechanics between uniform and recurrent swimming to light intensity changes and perform on-demand turning under continuous light irradiation. Fueled by water and remotely powered by light, this unique hydrogel oscillator enables easy control over the oscillation dynamics and modes, offering an effective approach to self-adaptive soft robots and solar steam engines.
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- Award ID(s):
- 1808788
- NSF-PAR ID:
- 10382339
- Date Published:
- Journal Name:
- Science Robotics
- Volume:
- 6
- Issue:
- 61
- ISSN:
- 2470-9476
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/scirobotics.abi4523
