Tom Kamperman

In-air microfluidics enables rapid fabrication of emulsions, suspensions, and 3D modular (bio)materials

Designer microparticles and multiscale materials can be fabricated in one step by microfluidic processing in the air. Microfluidic chips provide unparalleled control over droplets and jets, which have advanced all natural sciences. However, microfluidic applications could be vastly expanded by increasing the per-channel throughput and directly exploiting the output of chips for rapid additive manufacturing. We unlock these features with in-air microfluidics, a new chip-free platform to manipulate microscale liquid streams in the air. By controlling the composition and in-air impact of liquid microjets by surface tension–driven encapsulation, we fabricate monodisperse emulsions, particles, and fibers with diameters of 20 to 300 μm at rates that are 10 to 100 times higher than chip-based droplet microfluidics. Furthermore, in-air microfluidics uniquely enables module-based production of three-dimensional (3D) multiscale (bio)materials in one step because droplets are partially solidified in-flight and can immediately be printed onto a substrate. In-air microfluidics is cytocompatible, as demonstrated by additive manufacturing of 3D modular constructs with tailored microenvironments for multiple cell types. Its in-line control, high throughput and resolution, and cytocompatibility make in-air microfluidics a versatile platform technology for science, industry, and health care.

Nanoemulsion-induced enzymatic crosslinking of tyramine-functionalized polymer droplets

In situ gelation of water-in-oil polymer emulsions is a key method to produce hydrogel particles. Although this approach is in principle ideal for encapsulating bioactive components such as cells, the oil phase can interfere with straightforward presentation of crosslinker molecules. Several approaches have been developed to induce in-emulsion gelation by exploiting the triggered generation or release of crosslinker molecules. However, these methods typically rely on photo- or acid-based reactions that are detrimental to cell survival and functioning. In this work, we demonstrate the diffusion-based supplementation of small molecules for the in-emulsion gelation of multiple tyramine-functionalized polymers via enzymatic crosslinking using a H2O2/oil nanoemulsion. This strategy is compatible with various emulsification techniques, thereby readily supporting the formation of monodisperse hydrogel particles spanning multiple length scales ranging from the nano- to the millimeter. As proof of principle, we leveraged droplet microfluidics in combination with the cytocompatible nature of enzymatic crosslinking to engineer hollow cell-laden hydrogel microcapsules that support the formation of viable and functional 3D microtissues. The straightforward, universal, and cytocompatible nature of nanoemulsion-induced enzymatic crosslinking facilitates its rapid and widespread use in numerous food, pharma, and life science applications.

Ultra-high-throughput Production of Monodisperse and Multifunctional Janus Microparticles using in-air Microfluidics

Compartmentalized Janus microparticles advance many applications ranging from chemical synthesis to consumer electronics. Although these particles can be accurately manufactured using microfluidic droplet generators, the per-nozzle throughputs are relatively low (∼μL/min). Here, we use “in-air microfluidics” to combine liquid microjets in midair, thereby enabling orders of magnitude faster production of Janus microparticles (∼mL/min) as compared to chip-based microfluidics. Monodisperse Janus microparticles with diameters between 50 and 500 μm, tunable compartment sizes, and functional cargo are controllably produced. Furthermore, these microparticles are designed as magnetically steerable microreactors, which represents a novel tool to perform enzymatic cascade reactions within continuous fluid flows

Single-Cell Microgels: Technology, Challenges, and Applications

Single-cell-laden microgels effectively act as the engineered counterpart of the smallest living building block of life: a cell within its pericellular matrix. Recent breakthroughs have enabled the encapsulation of single cells in sub-100-μm microgels to provide physiologically relevant microniches with minimal mass transport limitations and favorable pharmacokinetic properties. Single-cell-laden microgels offer additional unprecedented advantages, including facile manipulation, culture, and analysis of individual cell within 3D microenvironments. Therefore, single-cell microgel technology is expected to be instrumental in many life science applications, including pharmacological screenings, regenerative medicine, and fundamental biological research. In this review, we discuss the latest trends, technical challenges, and breakthroughs, and present our vision of the future of single-cell microgel technology and its applications.

Microgel Technology to Advance Modular Tissue Engineering

The field of tissue engineering aims to restore the function of damaged or missing tissues by combining cells and/or a supportive biomaterial scaffold into an engineered tissue construct. The construct’s design requirements are typically set by native tissues – the gold standard for tissue engineers. Closely observing native tissues from an engineering perspective reveals a complex multiscale modular design. This natural architecture is essential for proper tissue functioning, but not trivial to manufacture. Recapitulating the complexity of native tissues requires high-resolution manufacturing technologies such as microfluidics. However, increasing resolution is typically at the cost of production throughput and vice versa, which hampers the clinical translation of complex tissue engineering strategies. New advanced concepts that integrate both high-resolution and rapid additive manufacturing techniques are thus prerequisite to upgrade the field of modular tissue engineering. This thesis describes: i) the development of various innovative biomaterials and microfluidic platforms for the production of (cell-laden) hydrogel microparticles (i.e. microgels) that act as tissue engineering building blocks; ii) the modification of microgels with in situ tunable biomechanical and biochemical properties to enable specific tailoring of the cellular microenvironment; iii) their incorporation into modular bio-inks, which is a novel concept to enable the facile engineering of complex tissues using standard biofabrication methods; and iv) the invention of a platform technology called ‘in-air microfluidics’ (IAMF), which uniquely enables the chip-free micromanufacturing of droplets, particles, and 3D modular biomaterials at rates that are readily compatible with clinical applications. Together, this thesis introduces a number of innovative biomaterial modifications and microfluidics-based manufacturing concepts that facilitate the development and clinical translation of modular tissue engineering applications.