Colloid

Engineering

Chemical physics

Resist

Biology

Materials science

Soft matter

Soft robotics

Layer (electronics)

Actuator

Absorption (acoustics)

Computer science

Chemical engineering

Photonics

Polymer

Physics

Nanotechnology

Amplitude

Optics

Lithography

Microstructure

Artificial intelligence

Composite material

Biological system

Optoelectronics

Nature Communications

Stimuli-responsive microstructures are critical to create adaptable systems in soft robotics and biosciences. For such applications, the materials must be compatible with aqueous environments and enable the manufacturing of three-dimensional structures. Poly(N-isopropylacrylamide) (pNIPAM) is a well-established polymer, exhibiting a substantial response to changes in temperature close to its lower critical solution temperature. To create complex actuation patterns, materials that react differently with respect to a stimulus are required. Here, we introduce functional three-dimensional hetero-microstructures based on pNIPAM. By variation of the local exposure dose in three-dimensional laser lithography, we demonstrate that the material parameters can be altered on demand in a single resist formulation. We explore this concept for sophisticated three-dimensional architectures with large-amplitude and complex responses. The experimental results are consistent with numerical calculations, able to predict the actuation response. Furthermore, a spatially controlled response is achieved by inducing a local temperature increase by two-photon absorption of focused light.

Controlling the shape of 3D microstructures by temperature and light