Fabrication, Flow Assembly, and Permeation of Microscopic Any‐Shape Particles

Abstract

Today, millimeter‐sized nonspherical any‐shape particles serve as flexible, functional scaffold material in chemical and biochemical reactors tailoring their hydrodynamic properties and active surface‐to‐volume ratio based on the particle's shape. Decreasing the particle size to smaller than 100 μm would be desired as it increases the surface‐to‐volume ratio and promotes a particle assembly based on surface interactions, allowing the creation of tailored self‐assembling 3D scaffolds. This study demonstrates a continuous high‐throughput fabrication of microscopic 3D particles with complex shape and sub‐micron resolution using continuous two‐photon vertical flow lithography. Evolving from there, in‐channel particle fabrication into a confined microfluidic chamber with a resting fluid enables the precise fabrication of a defined number of particles. 3D assemblies with various particle shapes are fabricated and analyzed regarding their permeability and morphology, representing convective accessibility of the assembly's porosity. Differently shaped particles highlight the importance of contact area regarding particle–particle interactions and the respective hydraulic resistance of an assembly. Finally, cell culture experiments show manifold cell–particle interactions promising applicability as bio‐hybrid tissue. This study pushes the research boundaries of adaptive, responsive, and permeable 3D scaffolds and granular media by demonstrating a high throughput fabrication solution and a precise hydrodynamic analysis method for micro‐particle assemblies.

Femtosecond laser direct writing of functional stimulus-responsive structures and applications

“…Stimulus-responsive structures prepared by FsLDW technology are being increasingly utilized in biomedical fields including cell delivery and precisely localized therapy because of their controllable dynamic behaviors of manipulating micro-objects and potential capabilities for loading, delivery, and release of drugs [252][253][254][255][256][257][258]. Cells are capable of recognizing and transmitting mechanical strain and stress pattern through mechanically sensitive modules, including cell adhesion sites, ion channels, and cytoskeleton.…”

Recent Advances in Multi‐Photon 3D Laser Printing: Active Materials and Applications

“…This method was reported mainly for the continuous synthesis of polymeric particles or structures. [ 178–181 ] For example, Lölsberg et al. prepared a microfluidic device that was successfully used for the 3D printing of a polymeric microtube in a vertical fluid‐flow setup.…”

Toward the Next Generation of Neural Iontronic Interfaces

“…From the material side, it is becoming evident that striving toward softer materials (in the 10-100 kPa range), such as hydrogels or viscoelastic materials, achieve tighter interaction with biological tissue. [42,[78][79][80][81] These materials bear the potential for lifelong implantation and continuous monitoring and interaction with the surrounding tissue by further displaying biomimetic (and conductive) tissue-like architectures, which can be achieved through innovative techniques such as additive manufacturing and bioprinting. However, it is still challenging to create devices with such materials with a high electrode count, as they are not compatible with standard microfabrication techniques and chemicals, thereby introducing many extra steps that make the processing highly manual and labor-intensive.…”