3D-printed low-voltage-driven ciliary hydrogel microactuators

Area of Science:

• Soft robotics
• Bio-inspired engineering
• Microfluidics

Background:

• Natural cilia are vital for biological processes like locomotion and cell trafficking.
• Replicating natural cilia's complex 3D motion in artificial systems is a significant engineering challenge.
• Existing micro-scale actuation methods have limitations in scalability and local control.

Purpose of the Study:

• To investigate the electrical response of micro-scale hydrogels for actuation.
• To develop artificial micro-cilia capable of dynamic, 3D motion.
• To enable new microscale devices and bio-inspired technologies.

Main Methods:

• Utilized two-photon polymerization to 3D print a nanometre-scale hydrogel network.
• Explored the fast electrical response of acrylic acid-co-acrylamide (AAc-co-AAm) hydrogels to low voltages (down to 1.5V).
• Fabricated arrays of gel micro-cilia (2-10 µm diameter, 18-90 µm height) that actuate via ion migration.

Main Results:

• Demonstrated millisecond-scale bending motions in hydrogels driven by ion migration.
• Achieved 3D rotational bending motion in gel micro-cilia up to 40 Hz, mimicking natural cilia.
• Showcased high durability with <30% degradation after 330,000 actuation cycles.
• Integrated gel micro-cilia on flexible substrates for large-scale fabrication and individual control.

Conclusions:

• Developed a novel method for creating artificial cilia with dynamic 3D motion using responsive hydrogels.
• The gel micro-cilia exhibit high performance, durability, and scalability for microfluidic applications.
• This technology opens avenues for advanced bio-inspired devices and understanding of ciliary dynamics.