Advanced Materials Technologies

Blood-based biomarkers are central to diagnostics, yet current approaches depend on invasive sampling and centralized laboratory infrastructure. At the same time, womens reproductive health remains severely under-monitored: most clinically relevant biomarkers are rarely measured outside fertility clinics, leaving millions without accessible, continuous insight into their reproductive lifespan. Anti-Mullerian hormone (AMH), a key indicator of ovarian reserve and overall reproductive function, still requires venous blood collection and specialized analysis, creating a major barrier to early detection, routine monitoring, and population-level screening. Here, we present a lateral flow assay (LFA) enabling direct AMH detection in unprocessed menstrual blood. The assay uses covalently conjugated 150 nm gold nanoshells to achieve sensitive colorimetric detection within the clinically relevant 0-10 ng/mL range. Results can be visually interpreted by naked-eye detection or quantified via a smartphone-based machine-learning algorithm for semi-quantitative assessment. The LFA performance correlates strongly with clinical chemistry lab-based analyses and can be seamlessly integrated into point-of-care formats, including wearable menstruation pads as well as simple dipstick tests. This technology provides a non-invasive, affordable, and robust solution for decentralized, regular monitoring of ovarian health.

Paper-based diagnostics such as lateral flow assays (LFAs) and microfluidic paper-based analytical devices ({micro}PADs) have attracted considerable attention because of their low cost, portability, and ease of use. Currently, to enable fabrication of {micro}PADs and improve LFA performance, hydrophobic blocks are patterned on paper substrates. However, fabrication of high-resolution hydrophobic barriers remains a major challenge. In this work, we developed a novel silicone extrudable ink for the fabrication of hydrophobic features on paper substrates. The ink was formulated using a vinyl-terminated polydimethylsiloxane (vPDMS) and polymethylhydrosiloxane (PMHS) system crosslinked through platinum-catalyzed hydrosilylation, and its rheological properties were tailored by incorporating silica fillers, obtaining a shear-thinning gel suitable for extrusion. The resulting formulation provided tunable properties, controlled deposition, and stable feature formation, enabling simple, low-cost, rapid, and robust fabrication of high-resolution hydrophobic barriers. Using this approach, we demonstrated improved fluid confinement and pattern fidelity on paper substrates, fabricated high-resolution paper microfluidic devices down to 150 {micro}m channel width, and enhanced the sensitivity of an LFA for a malaria diagnostic test. These results highlight the potential of this silicone ink platform as a practical and scalable strategy for advancing high-performance paper-based diagnostic technologies.

Oxygen availability is a critical yet all-too-often overlooked variable in organ-on-a-chip (OoC) systems. PDMS-based microfluidics remain the most common approach to facilitating oxygen equilibration with the incubator environment, but the materials tendency to ad- and absorb small hydrophobic molecules can pose significant concerns for pharmacological and toxicological studies. Yet there remains a lack of alternative gas-exchange materials feasible for OoC integration, even as the use of thermoplastic microfluidics in particular has otherwise proliferated. Here, we present commercially available track-etched nanoporous polycarbonate (50 nm pores, 1.18% porosity, [~]0.1 {euro}/cm2) as a practical alternative to polydimethylsiloxane (PDMS) for gas exchange in OoC. We show that nanoporous polycarbonate provides a thermoplastic material with an oxygen permeability of 3290 {+/-} 240 fs mol / kg, over an order of magnitude higher than PDMS. We demonstrate integration into existing lamination-based thermoplastic microfluidic fabrication workflows with sustained leak-free operation well above physiologically relevant pressures. We find that nanoporous polycarbonate does not compromise cell viability, but that high water vapor permeance necessitates a high-humidity environment around the device - though thickness-normalized water vapor permeability is notably similar to PDMS. We validate the OoC application with Caco-2 intestinal epithelial cells by monitoring oxygen levels during the critical cell attachment phase, with nanoporous polycarbonate allowing for maintenance of stable oxygen tension, in stark contrast to severe hypoxia in nonporous controls within 30 minutes. We further show that this uncontrolled hypoxia correlates with a time-delayed increase in cellular hypoxia inducible factor-1 reporter expression. Overall, our findings position nanoporous polycarbonate as a low-cost, mechanically robust, and fabrication-friendly alternative that can bring controlled oxygen availability to PDMS-free microfluidics and OoC.

Microphysiological systems (MPSs) have shown great promise for the advancement of drug discovery and toxicological tests, and as an alternative to animal models. However, although several chips and systems have been reported, some important issues are yet to be addressed, such as the use of polydimethylsiloxane (PDMS). Cyclo olefin polymers (COPs) have advantages over other thermoplastic materials, but most COP-based MPSs use solvent bonding during fabrication, which can affect any cells they are used to culture. This study uses a photobonding process with vacuum ultraviolet (UVU) to produce MPSs without the need for solvents such as cyclohexane, dichloromethane, and toluene. This is then used for comparison to investigate the effects of solvents on cell cultures. Quantitative immunofluorescent assays show that the coating efficiencies of extracellular matrix proteins, such as Matrigel and collagen I, are reduced on solvent-treated COP surfaces, compared with those prepared using VUV photobonding. Furthermore, SH-SY5Y neuroblastoma cells are used to evaluate cytotoxicity. This shows that solvent-MPSs induce apoptosis, but VUV-MPSs do not. These results provide insights into solvent bonding for MPS fabrication so that undesirable reactions can be avoided. Moreover, this work may be used to standardize MPS protocols and establish good manufacturing practices.

The ability to rapidly fabricate custom polydimethylsiloxane (PDMS) devices is central to advancing organ-on-a-chip (OoC) technologies and other biological microplatforms. However, traditional photolithography and the surface roughness of directly 3D printed molds limit their accessibility and scalability of PDMS-based systems. Photolithographic workflows are limited by their dependence on specialized equipment, technical expertise, dedicated fabrication infrastructure, and are typically restricted to planar geometries and microscale features, limiting their use for millifluidic or complex 3D device features. To address these challenges, we present a modular workflow for the robust fabrication of PDMS-based devices using stereolithography (SLA) or fused deposition modeling (FDM) printing combined with optimized epoxy coatings. Acetone-thinned epoxy formulations dramatically improve SLA printed mold smoothness, eliminate tearing during demolding, and yield PDMS replicas with clean, well-defined structural features. For FDM printed molds, a two-step epoxy coating strategy restores mold quality sufficient for robust replica molding. The resulting PDMS devices support irreversible glass bonding, fluid containment, and cell culture applications, validated using normal mammary epithelial and cancer cell lines. We further demonstrate the formation of perfusable tissue aggregates within 3D matrices and introduce a low-cost 3D printed imaging platform for parallel live-cell imaging across four PDMS devices, showcasing its use for monitoring 20 OoC channels under gravity- or pump-driven flow. This versatile and reproducible method lowers the barrier to entry for soft lithography, allowing researchers without prior microfabrication expertise to rapidly prototype functional PDMS devices for diverse biological applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/645830v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@bbf403org.highwire.dtl.DTLVardef@191249forg.highwire.dtl.DTLVardef@1fb7bf2org.highwire.dtl.DTLVardef@1865e4c_HPS_FORMAT_FIGEXP M_FIG C_FIG

We report the fabrication of very thin microfluidic active and passive devices on rigid and flexible substrates for sample-space-restricted applications. Thin glass coverslips are commonly used substrates, but these being fragile often crack during experiments, leading to device failure. Here, we used PET as a flexible substrate to fabricate robust thin devices. We proposed a simpler process for PET-PDMS bonding without any silane, adhesive, and/or plasma treatment. We presented the compatibility of the thin devices with a digital in-line holographic microscope (DIHM) as a use case. The substitution of the conventional microscope with DIHM in microfluidic large-scale integrated systems renders simplicity, cost-effectiveness, portability, and miniaturization of the overall system. It also enables a customized and parallel multisite optical observation for a complex microfluidic circuit chip. These chips comprise various microfluidic components made of active microvalves, particularly Quake valves. We also successfully demonstrated the function of microvalves fabricated with our method to regulate the fluidic flow. Thus, are suited to making sophisticated microfluidic circuit chips to fit a variety of applications like organ-on-chip, cell culture, wearable biosensors, pressure sensors, etc.

Organ-on-chip (OoC) systems enable the recapitulation of key structural and functional characteristics of human tissues within controlled micro-engineered environments. In mechanically active tissues such as musculoskeletal, cardiac, and vascular systems, the incorporation of dynamic physical forces is essential for replicating the biomechanical cues governing cellular morphology and functional responses in-vivo. Without such stimuli, OoC models may fail to capture physiologically relevant tissue behaviors. Porous and semi-permeable membranes are critical components of OoCs, facilitating selective transport of nutrients, gases, and signaling molecules between cellular compartments to support biologically accurate barrier replication. Hence, fabrication strategies that permit precise modulation of membrane permeability are desirable to accommodate for the varying needs in pore size and porosity across organ systems. This study presents a two-stage fabrication process for stretchable, microporous polydimethylsiloxane (PDMS) membranes using femtosecond (fs-) pulse laser drilling. The laser-ablated pores exhibit a characteristic conical morphology, with diameters tapering from the laser entry to exit point. By modulating laser power and number of pulses, 6-15 m exit-end pore diameters were achieved in 50 m thick PDMS films. The membranes demonstrated strong mechanical resilience, with a 5-12% reduction in Youngs modulus after 500 cycles of strain loading. Furthermore, membranes fabricated at lower laser powers exhibited superior retention of elasticity, highlighting the influence of processing parameters on mechanical behavior. Cytocompatibility and permeability assessments confirmed that the membranes supported sustained cell viability and proliferation over at least three days. In size-restricted membrane pore geometries, cellular migration was constrained without any inhibition of biomolecular transport. This selective permeability is critical in multilayer OoC architectures, where a balance between biomolecular diffusion and cellular compartmentalization is necessary to preserve distinct tissue interfaces and functional organization. This work presents fs-laser micro-drilling as a robust and tunable fabrication strategy for producing mechanically resilient, selectively permeable PDMS membranes for physiologically relevant OoC applications.

Despite technological advances, the fabrication of multiscale, multi-material, and topologically complex 3D structures using soft hydrogel bioinks remains a challenge due to the inherent trade-offs between print size/resolution, bioink properties, and design complexity. In this work, we combine additive (macroscale) digital light projection (DLP) mode with subtractive (microscale) two-photon ablation (TPA) mode with multi-material exchange capability. We identify ideal hydrogel bioink formulations that are compatible with both DLP and TPA modes of processing. Technical challenges related to multimodal fabrication such as alignment of multiscale topologies to facilitate seamless media perfusion, soft-hard multi-material printing to facilitate handling of mechanically weak hydrogel constructs, and hydrogel swelling during printing, were resolved. To highlight the novelty of this hybrid platform, we fabricated centimeter-scale bioink constructs with embedded microscale perfusable topologies that cannot be achieved by isolated use of either DLP or TPA modes. This includes simpler microfluidic chips with independently perfusable microchannels to more complex 3D constructs with embedded, multiscale, perfusable dual-fluidic circuits that mimic the alveoli-capillary interface, or microfluidic chips with endothelialized microchannels. The unique ability of this multimodal platform to mimic in vivo-like multiscale complexities can be potentially used to develop next-generation organ-on-chips.

Light-based additive manufacturing methods have been widely used to print high-resolution 3D structures for applications in tissue engineering, soft robotics, photonics, and microfluidics, among others. Despite this progress, multi-material printing with these methods remains challenging due to constraints associated with hardware modifications, control systems, cross-contaminations, waste, and resin properties. Here, we report a new printing platform coined Meniscus-enabled Projection Stereolithography (MAPS), a vat-free method that relies on generating and maintaining a resin meniscus between a crosslinked structure and bottom window and to print lateral, vertical, discrete, or gradient multi-material 3D structures with little-to-no cross-contamination or waste. We also show that MAPS is compatible with a wide range of resins and can print complex multi-material 3D structures without requiring specialized hardware, software, or complex washing protocols. MAPSs ability to print structures with microscale variations in mechanical stiffness, opacity, surface energy, cell densities, and magnetic properties provides a generic method to make advanced materials for a broad range of applications.

3D spheroids, which closely replicate three-dimensional cell-cell and cell-extracellular matrix interactions, offer superior predictive capabilities compared to conventional 2D monolayer cultures, positioning them as forward-looking platforms in drug testing, cancer biology, and regenerative medicine. However, high-throughput generation of uniform sized spheroids is still a technological challenge. In one hand, the use of conventional ultra-low attachment (ULA) multiwell plates for this purpose is labour intensive and complex. On the other hand, the use of microfabricated facilities demands cutting-edge infrastructure such as clean room, photolithography, and microfluidic setup which are often unavailable for the resource constrained laboratories. In this study, we addressed these problems by developing a low-cost Do-It-Yourself (DIY), polydimethylsiloxane (PDMS) and agarose-based spheroid generation device, capable of producing and maintaining hundreds of spheroids with minimal user intervention. We have demonstrated two variants based on their size, termed here as S1 and S2 devices which fit into 6-well and 12-well plates, and can generate 600 and 1200 uniform-sized spheroids respectively. We validated our device with various cell lines including primary and cancerous cell lines. We further demonstrated the drug testing capabilities of the device by estimating the IC50 value of the anticancer drug Temozolomide on U87-MG. The value was comparable with the same obtained from the spheroids generated using conventional ULA plates. Additional attachment of a perfusion system made the device suitable for long-term spheroid culture without much user intervention. Furthermore, the devices can also be used for the production of spheroids with gradually changing diameters in a controlled manner, resembling a size gradient. This feature is useful for checking the effect of drugs on different-sized spheroids and for co-culturing spheroids with varying cell densities, mimicking the disease architecture. We have co-cultured two types of the placental trophoblast cells, i.e., extravillous trophoblast (HTR-8) and syncytiotrophoblast (BeWo) with varying densities. In summary, this paper demonstrates a unique DIY method for a high-throughput uniform-sized spheroid generation at a fraction of cost which can be deployed to resource-constrained labs.

Active implantable microscale reservoir-based drug delivery systems enabled novel and effective drug delivery concepts for both systemic and localized drug delivery applications. These systems typically consist of a drug reservoir and an active pumping mechanism for precise delivery of drugs. Here we present a stand-alone, refillable, scalable, and fully implantable microreservoir platform to be integrated with micropumps as a storing component of active implantable drug delivery microsystems. The microreservoir was fabricated with 3D-printing technology, enabling miniature, scalable, and planar structure, optimized for subcutaneous implantation especially in small animals (e.g., mouse), while being readily scalable for larger animals and human translation. Three different capacities of the microreservoir (1 L, 10 L, and 100 L) were fabricated and characterized all with 3 mm thickness. The microreservoir consists of two main parts: a cavity for long-term drug storage with an outlet microtubing (250 m OD, 125 m ID), and a refill port for transcutaneous refills through a septum. The cavity membrane is fabricated with thin Parylene-C layers using a polyethylene glycol sacrificial layer, minimizing restoring force and hence backflow, as fluid is discharged. This feature enables integration to normally-open mechanisms and improves pumping efficiency when integrated to normally-closed pumps. The results of in vitro optimization and characterization of the cavity membrane show 95% extraction percentage of the cavity with insignificant (2%) backflow due to restoring force of the membrane. The refill port septum thickness is minimized down to 1 mm by a novel pre-compression concept, while capable of ~65000 injections with 30 Ga non-coring needles without leakage under 100 kPa (4x greater than physiological backpressure). To demonstrate integrability of the microreservoir to an active micropump, the 10 L microreservoir was integrated to a micropump recently developed in our laboratory, making an implantable drug delivery microsystem. Two different microsystems were subcutaneously implanted in two mice, and the outlet microtubing was implanted into the round window membrane niche for infusion of a known ototoxic compound (sodium salicylate) at 50 nL/min for 20 min. Real-time shifts in distortion product otoacoustic emission thresholds and amplitudes were measured during the infusion. The in vivo results show a mean shift of 22.1 dB after 20 min for the most basal region, matching with syringe pump results. A biocompatibility experiment was performed on the microsystem for six months to assess design and fabrication suitability for chronic subcutaneous implantation and clinical translational development. The results demonstrate very favorable signs of biocompatibility for long-term implantation. Although tested here on mice for a specific inner ear application, this low-cost design and fabrication methodology is scalable for use in larger animals and human for different applications/delivery sites.

1This work describes a versatile and cost-effective cell culture method for growing adherent cells on a porous membrane using pressure-sensitive double-sided adhesives. This technique allows cell culture using conventional methods and easy transfer to microfluidic chip devices. To support the viability of our system, we evaluate the toxicity effect of four different adhesives on two distinct airway epithelial cell lines and show functional applications for microfluidic cell culture chip fabrication. We showed that cells could be grown and expanded on a "floating" membrane, which can be transferred upon cell confluency to a microfluidic chip for further analysis. The viability of cells and their inflammatory responses to IL-1{beta} stimulation was investigated. Such a technique would be useful to culture cells in a conventional fashion, which is more convenient and faster, and stimulate cells in an advanced model with perfusion when needed.

Stereolithography (SLA) 3D printing has become increasingly popular for fabricating microfluidic devices, with applications including hydrogel patterning and tissue modeling. In open-channel systems with surface tension-driven flow, 3D-printer-induced discrepancies in channel surface texture can significantly impact fluid flow and device performance. While previous work has focused on comparing different 3D printing methods for microchannel fabrication, the effect of device orientation during SLA printing on microchannel morphology and capillary-driven flow has not been systematically evaluated. Furthermore, there is minimal research elucidating the influence of channel surface texture on the flow of biologically relevant hydrogel precursors commonly used in organ-on-a-chip applications. Herein, we investigated the impact of print orientation on channel morphology, fluid wetting behavior, and fluid flow by comparing laser SLA-based parts where the length of the channel was tilted at 0{degrees}, 15{degrees}, 45{degrees}, or 90{degrees} during printing. We demonstrated that channel floor surface texture is greatly affected by print orientation: the highest axial surface roughness was measured in 15{degrees} printed channels, and the highest axial surface tortuosity-which describes the real length along the surface-was measured in 45{degrees} printed channels. Print angles of 15{degrees} and 45{degrees} also resulted in asymmetric roughness of the channel floor, which caused asymmetric wetting of glycerol solution. Surface tension-driven flow of glycerol solution, agarose precursor solution, and collagen precursor solution was affected by print orientation, in which the 45{degrees} printed flow devices had slowest flow for all test fluids. Root mean square roughness was not a reliable predictor of slower flow; instead, surface tortuosity should be considered. Potential alternatives to better theoretically model how print angle-induced surface texture affects open-channel flow are discussed as well. These findings provide a framework of fabrication considerations for laser SLA printing of open microchannels that can also be applied to other layer-by-layer, vat photopolymerization-based 3D printing technologies.

Cardiovascular diseases cause an estimated 17.9 million deaths globally each year (World Health Organization). Endothelial cells that line the vasculature and the endocardium are subjected to cyclic mechanical stretch. Deviation from physiological stretch can alter the endothelial function, having the risk of atherosclerosis and myocardial infarction. To understand the mechanical stretch effects, cell culture platforms that provide mechanical stretch have been developed. However, most of them have fixed strain and frequency, sometime not in the pathophysiological range. We thus developed a novel, electromagnetically driven, uniaxial stretching device, where cells were grown on a flexible polydimethylsiloxane (PDMS) membrane mounted onto a 3-D printed track. The strain of the membrane was readily controlled by tailoring the track design and the frequency was determined by electromagnetic actuation. Furthermore, the mechanical strain gradient was generated on a PDMS membrane with a tapered thickness. This strain gradient, ranging from 1.5% to 40%, covered both physiological and pathological vascular stretch ranges. When human vascular endothelial cells were subjected to the cyclic stretch, the cells exhibited strain-dependent cell and nuclear orientation and elongation perpendicular to the stretching direction, compared to the random cell and nuclear orientation under the static condition. However, the overstretching led to deviation from the aforementioned orientation and elongation, and impaired the tight junctions, leading to a leaky endothelium. This novel, versatile, cost-effective, pathophysiologically relevant stretching device provides a useful platform for advancement of vascular disease research and treatment.

High-throughput microfluidics has transformed biomedical research by enabling precise and parallel sample handling, but most devices are single-use due to channel occlusion and contamination from experiments. Alongside low fabrication yield and reduced experimental success associated with dense microfeatures, this creates a major bottleneck for scalable high-throughput applications. We present a rapid, reusable, and modular high-throughput microfluidic platform with integrated microvalves for automation. The platform employs a multilayer architecture consisting of a custom casing, PDMS layers with dense microfeatures for fluid handling and culture, and a glass substrate. Permanent bonding is applied only between control and fluid layers, while reversible bonding is used at all other interfaces, including the substrate. Because substrate is the primary cell-contact surface and can be readily detached, the remaining layers can be disassembled, thoroughly cleaned, and reused with minimal processing on a new substrate. This approach improves repeatability and experimental success while reducing preparation time from days to [~]2 hours. The disassemblable design also supports incorporation of application-specific layers between fluid layer and substrate, enhancing platform versatility for 3D culture. We validated performance through pressure/flow characterization and on-chip cell/organoid culture. Overall, our platform accelerates rapid high-throughput data generation across diverse biological applications.

Organ-on-chip (OoC) platforms are increasingly adopted for predictive in vitro testing. However, most remain limited by soft-lithography-derived 2.5D microfluidic architectures and non-physiological rigid materials, or bioprinting approaches that require complex and failure-prone post-fabrication assembly. Here, we present a versatile approach that integrates tomographic volumetric additive manufacturing (TVAM) directly within preassembled microfluidic chips, enabling rapid, contactless fabrication of freeform 3D OoCs. Leveraging our open-source optical simulation framework, Dr.TVAM, we perform TVAM in custom-designed chips, eliminating post-printing manual assembly steps that commonly lead to leakage, contamination, and poor reproducibility. This strategy, termed TVAM-in-a-chip, supports the generation of diverse 3D channel architectures in multiple biocompatible photoresins spanning a wide range of chemistries and mechanical properties, including cell-laden formulations. We demonstrate multi-channel designs, compatibility with confocal imaging, and dynamic culture of epithelial and endothelial models. Overall, TVAM-in-a-chip overcomes key limitations of current OoC technologies and paves the way for a new generation of scalable, biomimetic 3D platforms for advanced in vitro modeling.

Although recent wearable chronic wound (CWO) bandage technologies have opened up exciting opportunities for personalized CWO management, they still face significant obstacles due to the reliance on the wound bed exudate for sensing and delivering therapeutics. Flat, shallow, and desiccated wounds are difficult to collect wound exudate for sensing, and some wounds continuously exude, potentially washing delivered therapeutics out of the wound bed. Herein, we developed a hydrogel-forming microneedles (HFMNs) array-based multimodal transdermal dressing system that continuously monitors the on-site physiological conditions of CWOs in interstitial fluid (ISF) and offers healing capabilities. The unique polar array design enables the integration of six replaceable HFMNs sensing electrodes to target the desired wound-specific analytes in transdermal interstitial fluid (glucose, uric acid, pH, Na+, Cl-, K+, and temperature) based on their significance in reflecting the status of the CWOs. The hydrogel is composed of a biocompatible and swellable polymer - polyvinyl alcohol, and chitosan as a crosslinking agent, while the incorporation of MXene (Ti3C2Tx) nanosheets as conductive nanofillers facilitates the formation of 3D polymer hydrogel networks via hydrogen bonding. Further coating and functionalization of poly(3,4-ethylenedioxythiophene): polystyrene sulfate (PEDOT: PSS) and graphene oxide through a laser-scribed phase separation (LSPS) process improves the electrical conductivity and in-vivo water stability of the HFMNs as a result of the larger and interconnected PEDOT-rich domains. Importantly, anti-inflammatory and antibacterial properties of the hydrogel prevent wound infection and promote skin wound healing. Through the potential correlation between wound-affected ISF and wound bed exudate, this method bridges conventional and implantable dressing systems for commercialization.

The human vasculature is a complex, multiscale system comprising hierarchical networks of macroscale to microscopic vessels. Existing in vitro fabrication techniques often fail to bridge these disparate scales, as high-resolution methods like multiphoton ablation are too slow for replicating larger vessels, while 3D printing lacks the resolution for fine microscale features. Here, we report a "twisted wire templating" strategy capable of generating perfusable bifurcating hydrogel networks that seamlessly transition from the macro- to the micro-scale (2.3 mm to 140 {micro}m) through seven orders of bifurcations. By optimizing wire-twisting geometries and polyurethane dip-coating, we overcame instability-driven bead formation to ensure replication fidelity across the networks. Fabrication rigs were reconfigured from existing 2D planar layouts to 3D reconfigurable architectures to better replicate 3D vessel geometries which simultaneously reducing the laboratory footprint and fabrication times by 47%. Using a Taguchi orthogonal array, we further optimized surface chemistry and hydrogel composition to inhibit structural failure during template extraction, resulting in fully patent, perfusable networks. This method provides a robust, low-cost, and scalable foundation for creating physiologically representative vascular models for investigating multiscale disease mechanisms and organ-level tissue engineering.

Over the past decade, the integration of microgel-based granular hydrogels in biomedical technologies has experienced substantial growth due to the numerous benefits microgels offer. However, the inability to easily adopt uniform microgel fabrication workflows at scale constitutes a major bottleneck, or in some cases, a barrier-to-entry that stunts further growth of the field. The gold-standard technique for emulsion-based microgel production is through microfluidic droplet-generating devices that produce liquid gel precursor droplets that gel post-production. However, traditional microfluidic workflows often require multiple independent flows and controlled pressure sources, along with a steep learning curve in using microfluidics to achieve uniform droplet sizes reproducibly and repeatedly. This difficulty in adopting microgel fabrication is further compounded by low throughput and the extensive flow rate calibration required when switching to new formulations (e.g., material type, droplet size). In this work, we present a step-emulsion system that bridges the gap by providing a robust and simple setup. We experimentally characterize and evaluate how flow and outlet channel dimension contribute to the generation of uniform droplet populations at specific sizes. With our large dataset consisting of various outlet channel dimensions, we evaluated outlet channel geometrical impacts (height, width, cross-sectional area, aspect-ratio, etc.) on gel precursor droplet size and generation throughput. We demonstrate robust, highly compatible, and repeatably uniform droplet generation from various gel precursor polymer backbones, users with varying microfluidics experience, and a wide viscosity range, including alginate solutions with 650 times the viscosity of water. Furthermore, we confirmed consistent gel precursor droplet generation outcomes driven by a constant flow source (syringe pump) and by direct manual injection as a simple and highly adoptable option for the generation of gel precursor droplets. This platform is ideal for researchers seeking rapid and easy microgel fabrication, regardless of microfluidics experience.

Vat Photopolymerization (VPP) holds much promise for producing biomaterial constructs such as porous scaffolds. However, achieving micron-scale pore dimensions with precision presents a challenge. This study offers an innovative approach to stabilize the silicone elastomer vat surface permitting micron-scale layer thickness accuracy to be maintained. Internal and surface contamination on the poly(dimethyl siloxane) (PDMS) vat surface were observed and effectively controlled with a pre-saturation methodology, and porous structures with cubical pores were then printed with varying layer thicknesses. These structures demonstrate the ability to achieve micrometric resolution and layer thicknesses as fine as 32 {micro}m. A scaffold suitable for in vivo implantation with 40 {micro}m cubical pores was successfully printed within 5 hours using a stabilized PDMS vat surface. Additionally, the methodologys adaptability to intricate non-linear edge porous structures underscores its versatility across X, Y, and Z-axis.