3D inkjet printed self-propelled motors for micro-stirring

Area of Science:

• Materials Science
• Biomedical Engineering
• Microfluidics

Background:

• Microscopic self-propelled motors (SPMs) are actively researched, but macroscopic SPMs remain underexplored for biomedical applications.
• Regenerated silk fibroin (RSF) offers a versatile material for fabricating complex structures.
• Precise fabrication is key to controlling SPM behavior and optimizing performance.

Purpose of the Study:

• To test 3D reactive inkjet (RIJ) printing for fabricating millimetre-scale SPMs from RSF.
• To compare propulsion behaviors of different SPM geometries and mechanisms.
• To identify optimal SPM designs for enhancing diffusion-limited biomedical assays via induced fluid flow.

Main Methods:

• Fabricated millimetre-scale SPMs with four distinct geometric shapes using 3D RIJ printing of RSF.
• Investigated two propulsion mechanisms: catalysis-induced bubble generation and surface tension gradients.
• Utilized computational fluid dynamics (CFD) simulations to assess mixing enhancement in microwells.

Main Results:

• 3D RIJ printing successfully fabricated SPMs with controlled propulsion mechanisms and shapes.
• Surface tension-driven SPMs exhibited faster velocities and smoother deceleration than catalysis-driven SPMs.
• CFD simulations confirmed the viability of SPMs for enhancing mixing in small-volume biological assays.

Conclusions:

• Millimetre-scale SPMs can be precisely fabricated using 3D RIJ printing of RSF.
• Surface tension propulsion is more suitable for biomedical applications requiring controlled fluid movement.
• These SPMs hold potential for improving the sensitivity of diffusion-rate limited biomedical assays.