Biology subjects

Destgeer, G.

Publications and source records attributed to Destgeer, G..

12 recordsLinked to original sources

bioRxiv2026

Stop-Flow Lithography Using Hydrodynamic Flow Resistance Regulation and Hydraulic Compliance Minimization for Size-Tunable Anisotropic Multilayered Microparticles Fabrication

Stop-flow lithography (SFL) enables the fabrication of microparticles with designed geometries and material compositions, but its performance relies on rapid flow stopping, which remains particularly challenging in multi-inlet systems with high hydrodynamic flow resistance and hydraulic compliance. Here, we develop a pneumatic-controlled SFL platform with a framework based on flow resistance regulation and hydraulic compliance minimization for fabricating size-tunable anisotropic multilayered microparticles. Our analysis indicates that flow-stopping behavior is governed by the release of extra fluid volume stored in the system due to hydraulic compliance, which arises from the deformation of microfluidic components and the compressibility of the fluid within them. Through numerical modeling and analysis, we identify deformation in the PDMS inlet port region as the dominant contributor to the stored extra fluid volume. By regulating the flow resistance of the tubing relative to that of the outlet channel, the stored extra fluid volume can be preferentially released forward through the outlet or backward through the inlet tubing, enabling rapid flow stopping across configurations with 500, 250, and 100 m outlets. Furthermore, by supporting the PDMS membrane beneath the inlet region with a rigid glass substrate and reducing its dimensions, the hydraulic compliance and consequently the stored extra fluid volume are significantly reduced. With these strategies, microparticles with well-defined boundaries can be fabricated at short, flow-stopping, delay times, and the flow profiles obtained in multi-inlet systems can be preserved during flow stopping and transferred into particle patterns.

bioengineering↗

bioRxiv2026

Lab on a Capillary: Instrument-Free Compartmentalization Using Photopatterned Hydrogel Rings Embedded inside a Glass Capillary for Amplified Bioassays

Sensitive and low-cost protein biomarker detection is critical for disease diagnosis. Advanced microfluidic systems can generate miniature reaction compartments for a high-sensitivity assay. However, these platforms often require external instruments, skilled operators, and complex setups. Here, we develop a Lab on a Capillary (LabCap) platform that integrates photopatterned hydrogel rings within a glass capillary using a reconfigurable stop-flow lithography system. During sample loading and unloading steps, nanoliter-scale aqueous droplets (torodrops) are spontaneously formed around the hydrogel rings, creating isolated reaction compartments without the need for external instruments or an immiscible oil phase. The LabCap platform enables quantitative detection of clinically relevant biomarkers, including C-reactive protein (CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). By adjusting the incubation protocol, assay speed and sensitivity can be tuned to meet different analytical requirements. A periodic medium exchange protocol enables biomarker detection at concentrations as low as 1 ng/mL, whereas prolonged static incubation extends detection to 0.1 ng/mL. In addition, LabCap offers practical advantages, including low fabrication cost (<{euro}1 per device), low reagent consumption (<100 L per assay step), and minimal wash-buffer usage (1 mL). These results demonstrate that LabCap is a simple, cost-effective, and versatile platform for biomarker detection.

bioengineering↗

bioRxiv2026

Acoustofluidic Active Flow Sculpting Enables Dynamic, Reconfigurable Cross-Sectional Patterning

Soft materials created with flow lithography exhibit distinct functionality depending on the shape and material composition of the precursor fluids, enabling applications ranging from tissue engineering to anti-counterfeiting. However, current manufacturing techniques largely rely on static nozzle geometries or passive hydrodynamic focusing, which commit to a fixed structure during fabrication and limit the ability to actively reconfigure material architecture in continuous flow. Here, we introduce ActiSculpt, an acoustofluidic platform that replaces physical constructions with dynamic, programmable, non-invasive elements to configure the continuous flow. By exploiting the interplay between laminar stability and acoustic streaming, we decouple deterministic fluid deformation from chaotic mixing, enabling the precise sculpting of cross-sectional flow structures. We demonstrate the high-throughput generation of a diverse library of hydrogel particles with continuously tunable moments of inertia. We further demonstrate continuous fiber fabrication in which acoustic parameters are varied in real time, using temporal control to encode structural variation along the fiber's length. Finally, we translate this platform into a motion-controlled 3D printer, establishing printability of fully-curable and half-curable fiber configurations and confirming that acoustically programmed cross-sections, along with their capacity for multi-fiber structural assembly, are preserved in the printed output. The result is a platform that overcomes the one-device, one-geometry constraint of existing techniques, enabling not only on-demand reconfiguration between fabrication runs but real-time control of material architecture within a single continuous flow, extending from bench-scale characterization to an operating additive manufacturing process. This spatiotemporal control establishes a new design axis for engineering soft materials with programmable mechanical and functional properties.

bioengineering↗

bioRxiv2025

CellTrap: A Microfluidic Platform Enabling Cell-Cell Interactions at Variable Effector to Target Ratios

Immune-cancer cell interactions play a central role in understanding antitumor responses and evaluating immunotherapies. However, long-term, single-cell-level analysis of these interactions remains challenging. To address this, we developed a microfluidic trapping device with 1,024 traps, each equipped with a filter to retain cells, sustain medium flow, minimize cross-talk, and allow precise control of effector-to-target (E:T) ratios. The platform enables continuous monitoring of immune-cancer interactions for up to 14 hours. Device characterization was performed using 10 {micro}m fluorescent beads seeded via hydrostatic flow, with trap occupancy validated by Poisson statistics. Initial experiments using PBMCs against GFP-expressing U87 (U87GFP) glioblastoma cells demonstrated an immune-mediated reduction in GFP intensity, which was interpreted cautiously as a cytotoxic response. To improve reproducibility, we subsequently employed IL-2-stimulated Natural Killer cells (NK92IL2) as standardized effectors and evaluated their interactions with U87GFP glioblastoma cells, K562 chronic myelogenous leukemia cells, and LS174T adenocarcinoma cells. Time-lapse imaging revealed transient intracellular calcium fluxes, consistent with early activation of NK92IL2 cells, followed by a cytotoxic response. Increasing E:T ratios consistently enhanced immune activity, highlighting the utility of this device for dissecting immune-cancer interactions and guiding the development of immunotherapy.

bioengineering↗

bioRxiv2025

3D Hydrodynamic Flow Lithography

Continuous- and stop-flow lithography has been widely used for the fabrication of ingenious multi-dimensional microstructures, including fibers and microparticles. The flow profile of multiple co-flowing streams during the process, as one of the dimensions, dictates the cross-sectional morphology of the microstructures. Here, we introduce a three-dimensional hydrodynamic flow lithography (3D HFL) approach that enables rapid and programmable generation of desired flow profiles and their conversion into solid microstructures. By strategically combining multiple flow sculpting strategies, including variable inlet configurations, intra-channel pillar configurations, and outlet configurations, we achieved precise and versatile control over flow sculpting, as validated by computational fluid dynamics simulations and experimental production of microparticles and fibers, offering unparalleled design flexibility. Importantly, the flow sculpting device is fabricated using low-cost 3D-printed molds to cast PDMS channels with precisely aligned inlets and complex geometries that are difficult or impossible to achieve using conventional soft lithography. Our 3D HFL approach effectively overcomes the limitations of existing microfabrication techniques in device complexity, structural diversity, multi-material integration, and production throughput. Furthermore, we demonstrated the capability of this platform to produce anisotropic multi-material microparticles and fibers tailored for specific applications, such as amphiphilic particles for uniform microdroplet capture, biocompatible patterned hydrogels for controlled cell adhesion, and dual-layer fibers for temperature sensing. The simplicity of device fabrication, combined with the broad design flexibility, establishes this platform as a scalable, high-throughput, and versatile solution for engineering anisotropic microparticles and fibers with tailored functionalities, providing powerful tools for a wide range of downstream fields.

bioengineering↗

bioRxiv2024

Spatiotemporal control of a multilayered co-axial flow in a 3D printed microchannel with cascaded nozzles

Sculpting and stopping multilayered co-flowing streams is challenging due to inhomogeneous pressure distribution within a fluidic circuit composed of multiple interconnected microchannels having variable flow resistances. Here, we have investigated three different flow control methods to effectively stop a multilayered flow inside a 3D-printed microfluidic channel by bringing the average flow velocity from >100 mm s-1 to below a critical velocity of 200 {micro}m s-1 within a certain delay time tD of [~]2s. Firstly, we 3D printed a sequence of three concentric nozzles ([~]75 {micro}m) embedded serially inside the microchannel ([~]200 {micro}m) using a two-photon polymerization (2PP) method. Secondly, we used the 2PP-based 3D printed device to produce a structured coaxial flow of four streams with individual layer thicknesses of O(10 {micro}m) within the outlet section of the microchannel. Thirdly, we removed the pressure gradient across the fluidic circuit, from > 2 bar to [~]0 bar, to stop the multilayered flow and measured tD to assess the performance of the three stop flow methods. During the stop-flow phase, an inhomogeneous pressure gradient across different inlets resulted in a backflow to inlet channels with lower pressures. In the three stop-flow methods investigated, we systemically managed the fluidic capacitance to minimize a dimensionless backflow index (BFI) value from [~]0.3 (worst case) to [~]0.03 (best case) for a total flow rate ranging from 16.8 {micro}l min-1 to 168 {micro}l min-1. Finally, we have recommended the best stop-flow conditions, which resulted in a minimal delay time of tD [~] 2s and a BFI < 0.05.

bioengineering↗

bioRxiv2024

Tunable picoliter-scale dropicle formation using amphiphilic microparticles with patterned hydrophilic patches

Microparticle-templated droplets or dropicles have recently gained interest in the fields of diagnostic immunoassays, single-cell analysis, and digital molecular biology. Amphiphilic particles have been shown to spontaneously capture aqueous droplets within their cavities upon mixing with an immiscible oil phase, where each particle templates a single droplet. Here, we fabricated an amphiphilic microparticle with four discrete hydrophilic patches embedded at the inner corners of a square-shaped hydrophobic outer ring of the particle (4C particle). 3D computational fluid dynamics simulations predicted droplet formation dynamics and differing equilibrium conditions depending on the patterning configuration. Experiments recapitulated equilibrium conditions enabling tunable dropicle configurations with reproducible volumes down to [~]200pL templated by the amphiphilic particles. The dropicle configurations depended predominantly on the size of the hydrophilic patches of the 4C particles. This validated modeling approach can inform the design of dropicles with varying volumes and numbers per particle, which can be harnessed in new amplified bioassays for greater sensitivity, dynamic range, and statistical confidence.

bioengineering↗

bioRxiv2023

Numerical simulation and analysis of droplet formation within an amphiphilic particle

An instrument-free particle-templated droplet formation can be achieved upon simple mixing of amphiphilic particles with aqueous and oil phases in a well plate by using a common lab pipette. Here, a two-dimensional, two-phase flow model was established using a finite element method to mimic the droplet formation within a concentric amphiphilic particle, which consisted of an outer hydrophobic layer and an inner hydrophilic layer. Immiscible water and oil phases selectively interacted with the hydrophilic and hydrophobic layers of the particle, respectively, to form an isolated aqueous compartment within a cavity. Three extreme models were also simulated, including completely hydrophilic, completely hydrophobic, and oppositely amphiphilic particle, which indicated that a right order of the particle layers was necessary to capture the droplet inside the cavity. Moreover, we performed a systematic study of particle-templated droplet formation by varying the individual layer thicknesses of particle, particle height, interfacial tension between water and oil, contact angle of interface with different surfaces, velocity of incoming oil media, and distance between neighboring particles. The volume fraction of water droplet trapped within the target cavity region was calculated to characterize the droplet formation. Our work will help to optimize the particle fabrication process, predict the experiment droplet formation, and explain the physical mechanism underlying compartmentalization phenomena.

bioengineering↗

bioRxiv2023

Fabrication of Crescent Shaped Microparticles for Particle Templated Droplet Formation

Crescent-shaped hydrogel microparticles have been shown to template uniform volume aqueous droplets upon simple mixing with aqueous and oil media for various bioassays. This emerging "lab on a particle" technique requires hydrogel particles with tunable material properties and dimensions. The crescent shape of the particles is attained by aqueous two-phase separation of polymers inside a spherical droplet followed by photopolymerization of the curable precursor. In this work, we have investigated the phase separation of photo-curable poly(ethylene glycol) diacrylate (PEGDA, Mw 700) and dextran (Mw 40,000) for tunable manufacturing of crescent-shaped particles. The particles morphology was precisely tuned by following a phase diagram, varying the UV intensity, and adjusting the flow rate ratio between the three streams, containing PEGDA, dextran, and oil, within a microfluidic droplet generation device. The fabricated particles with variable cavity sizes and outer diameters encapsulated uniform aqueous droplets upon mixing with a continuous oil phase. The particles were fluorescently labeled with red and blue emitting dyes at variable concentrations to produce six color-coded particles. The blue fluorescent dye showed a moderate response to the pH change from 1 to 7 in terms of an increase in emitted intensity. The fluorescently labeled particles were able to tolerate an extremely acidic solution (pH 1) but disintegrated within an extremely basic solution (pH 14). The particle-templated droplets were able to effectively retain the disintegrating particle and the fluorescent signal at pH 14, indicating completely segregated compartments.

bioengineering↗

bioRxiv2023

Fabrication of size-coded amphiphilic particles with a configurable 3D-printed microfluidic device for the formation of particle-templated droplets

Compartmentalizing an aqueous media into numerous nanoliter-scale droplets has substantially improved the performance of amplification assays. Particle-templated droplets or dropicles offer a user-friendly workflow for creating uniform volume compartments upon simple mixing of reagents and particles by using common laboratory apparatus. Amphiphilic shape-coded particles have been demonstrated to spontaneously hold aqueous droplets within hydrophilic cavities for multiplexed diagnostic assays. Here, we have proposed a configurable 3D-printed microfluidic device for the tunable fabrication of amphiphilic size-coded particles. The device was configured with multiple outlet tubings of different diameters and photomasks of variable slit lengths to fabricate a wide range of size-coded particles. We have fabricated >10 unique particle codes using a single reconfigurable device. The cross-sectional profile of the particles was further engineered by tuning the flow rate ratios of precursor streams to vary the inner and outer diameters of the particles and the thicknesses of the inner hydrophilic and outer hydrophobic layers. A range of cavity diameters and particle lengths enabled dropicle volumes of [~]1nL to [~]30nL. The fabricated particles were characterized by their ability to hold uniform droplet volumes and to orient themselves facing upwards or sideways in a well plate based on their aspect ratios.

bioengineering↗

bioRxiv2023

Amphiphilic particle-stabilized nanoliter droplet reactors with a multi-modal portable reader for distributive biomarker quantification

Compartmentalization, leveraging microfluidics, enables highly sensitive assays; but the requirement for significant infrastructure for their design, build, and operation limits access. Newer multi-material particle-based technologies thermodynamically stabilize monodisperse droplets as individual reaction compartments with simple liquid handling steps, precluding the need for expensive microfluidic equipment. Here, we further improve the accessibility of this lab on a particle technology to resource-limited settings by combining this assay system with a portable multi-modal reader, thus enabling nanoliter droplet assays in an accessible platform. We show the utility of this platform in measuring N-terminal propeptide B-type natriuretic peptide (NT-proBNP), a heart failure biomarker, in complex medium and patient samples. We report a limit of detection of [~]0.05 ng/ml and a linear response between 0.2 - 2 ng/ml in spiked plasma samples. We also show that, owing to the plurality of measurements per sample, "swarm" sensing acquires better statistical quantitation with a portable reader. Monte Carlo simulations show the increasing capability of this platform to differentiate between negative and positive samples, i.e. below or above the clinical cut-off for acute heart failure ([~]0.1ng/ml), as a function of the number of particles measured. Our platform measurements correlate with gold standard ELISA measurement in cardiac patient samples, and achieve lower variation in measurement across samples compared to the standard well plate-based ELISA. Thus, we show the capabilities of a cost-effective droplet-reader system in accurately measuring biomarkers in nanoliter droplets for diseases that disproportionally affect underserved communities in resource-limited settings.

bioengineering↗

bioRxiv2020

Formation of uniform reaction volumes using concentric amphiphilic microparticles

Reactions performed in uniform microscale volumes have enabled numerous applications in the analysis of rare entities (e.g. cells and molecules), however, sophisticated instruments are usually required to form large numbers of uniform compartments. Here, uniform aqueous droplets are formed by simply mixing microscale multi-material particles, consisting of concentric hydrophobic outer and hydrophilic inner layers, with oil and water. The particles are manufactured in batch using a 3D printed device to co-flow four concentric streams of polymer precursors which are polymerized with UV light. The size of the particles is readily controlled by adjusting the fluid flow rate ratios and mask design; whereas the cross-sectional shapes are altered by microfluidic nozzle design in the 3D printed device. Once a particle encapsulates an aqueous volume, each "dropicle" provides uniform compartmentalization and customizable shape-coding for each sample volume to enable multiplexing of uniform reactions in a scalable manner. We implement an enzymatically-amplified affinity assay using the dropicle system, yielding a detection limit of <1 pM with a dynamic range of at least 3 orders of magnitude. Moreover, multiplexing using two types of shape-coded particles was demonstrated without cross talk, laying a foundation for democratized single-entity assays.

bioengineering↗