During extrusion-based bioprinting, the deposited bioink filaments are subjected to deformations, such as collapse of overhanging filaments, which compromises ability stack several layers bioink, and fusion between adjacent resolution maintenance a desired pore structure. When developing new bioinks, approaches assess their shape fidelity after printing would be beneficial evaluate degree deformation filament estimate how similar final printed construct design. However, has been prevalently...

The energy budget and dissipation mechanisms during droplet impact on solid surfaces are studied numerically theoretically. We find that for high velocities negligible surface friction at the (i.e. free-slip), about one half of initial kinetic is transformed into energy, independent parameters detailed loss mechanism(s). argue this seemingly universal rule related to deformation mode reminiscent pipe flow undergoing a sudden expansion, which head can be calculated by multiplying incoming...

3D printing of common metals is highly challenging because are generally solid at room conditions. Copper and gold pillars manufactured with a resolution below 5 μm height up to 2 mm, using laser-induced forward transfer create eject liquid metal droplets. The solidified drop's shape crucial for discussed as function the laser energy.

Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s⁻¹.

Tailoring the hydrodynamic boundary condition is essential for both applied and fundamental aspects of drag reduction. Hydrodynamic friction on superhydrophobic substrates providing gas–liquid interfaces can potentially be optimized by controlling interface geometry. Therefore, establishing stable optimal crucial but rather challenging. Here we present unique microfluidic devices that allow presence controllable microbubbles at microchannels. We experimentally numerically examine effect...

Combining a laser pulse with liquid in microcapillary tubes series of experiments, fluid-mechanics group at University Twente finds new way generating highly focused and ultrafast jets understands how to control the jet speed.

Polymer foams are cellular solids composed of solid and gas phases, whose mechanical, thermal, acoustic properties determined by the composition, volume fraction, connectivity both phases. A new high-throughput additive manufacturing method, referred to as direct bubble writing, for creating polymer with locally programmed size, is reported. Direct writing relies on rapid generation patterning liquid shell-gas core droplets produced using a core-shell nozzle. The printed able retain their...

Abstract Biofabrication commonly involves the use of liquid droplets to transport cells printed structure. However, viability after impact is poorly controlled and understood, hampering applications including cell spraying, inkjet bioprinting laser-assisted transfer. Here, we present an analytical model describing as a function cell-surrounding droplet characteristics. The connects (1) survival membrane elongation, (2) elongation cell-containing size velocity (3) substrate properties....

The impact of a laser pulse on microdrop opaque liquid induces spectacular response: drop is propelled forward rapidly, and strongly deformed until it breaks up or even explodes. A detailed understanding this process crucial for generating extreme-ultraviolet (EUV) light in nanolithography. authors reveal that droplet propulsion driven by localized boiling the illuminated side subsequent expansion, proportion to energy pulse.

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 directly exploiting output of for rapid additive manufacturing. We unlock these features with in-air microfluidics, a new chip-free platform to manipulate microscale liquid streams in air. By controlling composition impact microjets surface tension-driven encapsulation, we...

Water microdroplet impact at velocities up to 100 m s−1 for droplet diameters ranging from 12 μm is studied. This parameter range covers the transition capillary-limited viscosity-limited spreading of impacting droplet. Splashing absent all measurements; droplets always gently spread over surface. The maximum radius compared several existing models. model by Pasandideh-Fard et al. agrees well with measured data, indicating importance a thin boundary layer just above surface, in which most...

Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, thermocouple with thickness 10 µm and height 250 µm, consisting platinum gold pillars is demonstrated. Multimaterial LIFT enables manufacturing the micrometer to millimeter range, i.e., between lithography other 3D printing technologies. As service our authors readers, this journal provides supporting information supplied authors. Such materials peer...

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" combine liquid microjets in midair, thereby enabling orders of magnitude faster production (∼mL/min) as compared chip-based microfluidics. Monodisperse with diameters between 50 and 500...

Single-cell-laden microgels support physiological 3D culture conditions while enabling straightforward handling and high-resolution readouts of individual cells. However, their widespread adoption for long-term cultures is limited by cell escape. In this work, it demonstrated that escape predisposed to off-center encapsulated High-speed microscopy reveals cells are positioned at the microgel precursor droplets' oil/water interface within milliseconds after droplet formation. conventional...

Laser-induced forward transfer (LIFT) allows for high-resolution three-dimensional printing of e.g. small metal droplets, which inkjet is not an option. Although the technique almost 30 years old, a detailed understanding its physics has been lacking. The authors observe and explain high-speed mechanisms behind ejection pure microdrops during LIFT, further parameter optimization particular job.

The dissolution process of small (initial (equivalent) radius $R_{0}<1$ mm) long-chain alcohol (of various types) sessile droplets in water is studied, disentangling diffusive and convective contributions. latter can arise for high solubilities the alcohol, as density alcohol–water mixture then considerably less than that pure water, giving rise to buoyancy-driven convection. flow around measured, using micro-particle image velocimetry ( ${\rm\mu}$ PIV) schlieren technique. When...

Oblique drop impact onto a deep liquid pool may result in deposition, single-sided splashing, or omnidirectional splashing. Here we experimentally study these different regimes as well the maximum cavity dimensions, and complement our findings with basic scaling arguments.

Power minimisation in branched fluidic networks has gained significant attention biology and engineering. The optimal network is defined by channel radii that minimise the sum of viscous dissipation volumetric energetic cost fluid. For limit cases including laminar flows, high Reynolds number turbulence, or smooth approximations, solutions are known. However, no single optimisation approach captures these cases. Furthermore, realistic exhibit intermediate points parameter space can hardly be...

This is a study motivated by the need to develop needle-free device for eliminating major global healthcare problems caused needles. The generation of liquid jets means continuous-wave laser, focused into light absorbing solution, was studied with aim developing portable and affordable jet injector. We designed fabricated glass microfluidic devices, which consist chamber where thermocavitation created tapered channel. growth vapor bubble displaces expels through channel as fast traveling...

When two liquids with different surface tensions come into contact, the liquid lower tension spreads over other liquid. This Marangoni-driven spreading has been studied for various geometries and surfactants, but dynamics of miscible in binary geometry (drop-drop) hardly investigated. Here we use stroboscopic illumination by nanosecond laser pulses to temporally resolve distance L(t) which a low-surface-tension drop high-surface-tension drop. is measured as function time, t, differences...

Abstract Microcapsules with a liquid core and solid shell composed of hydrophobic nanoparticles are broadly applied in food, pharmaceutics, biotechnologies. For example, Pickering emulsions, colloidosomes, or antibubbles (droplets surrounded by air layers water) enable controlled release active agents, biocompatibility, contact‐less transportation. However, producing nanoparticle‐ polymer‐laden shells at scale is highly challenging, since bulk methods polydisperse microfluidic chips prone to...

Fabrication of macroporous polymers with functionally graded architecture or chemistry bears transformative potential in acoustic damping, energy storage materials, flexible electronics, and filtration but is hardly reachable current processes. Here, we introduce thiol-ene chemistries direct bubble writing, a recent technique for additive manufacturing foams locally controlled cell size, density, macroscopic shape. Surfactant-free solvent-free three-dimensional (3D) without drying-induced...

Abstract Recent advances in optical coding, drug delivery, diagnostics, tissue engineering, shear‐induced gelation, and functionally engineered rheology crucially depend on microparticles microfibers with tunable shape, size, composition. However, scalable manufacturing of the required complex micromaterials remains a long‐standing challenge. Here in‐air polymerization liquid jets is demonstrated as novel platform to produce composition at high throughput (>100 mL h −1 per nozzle). The...