Nanoscale biological particles, such as lipoproteins (10–80 nm) or extracellular vesicles (30–200 nm), play pivotal roles in health and disease, including conditions like cardiovascular disorders and cancer. Their effective analysis is crucial for applications in diagnostics, quality control, and nanomedicine development. While elasto-inertial focusing offers a powerful method to manipulate particles without external fields, achieving consistent focusing of nanoparticles (<500 nm) has remained a challenge. In this study, elasto-inertial focusing of nanoparticles as small as 25 nm is experimentally demonstrated using straight high-aspect-ratio microchannels in a sheathless flow. Systematic investigations reveal the influence of channel width, particle size, viscoelastic concentration, and flow rate on focusing behavior. Additionally, through numerical simulations and experimental validation, insights are provided into particle migration dynamics and viscoelastic forces governing nanoparticle focusing. Finally, biological particles, including liposomes (90–140 nm), extracellular vesicles (100 nm), and lipoproteins (10–25 nm) is successfully focused, under optimized conditions, showcasing potential applications in medical diagnostics and targeted drug delivery. These findings mark a significant advancement toward size-based high-resolution particle separation, with implications for biomedicine and environmental sciences.

Organic electrochemical transistors (OECTs) are promising devices for bioelectronics, such as biosensors. However, current cleanroom-based microfabrication of OECTs hinders fast prototyping and widespread adoption of this technology for low-volume, low-cost applications. To address this limitation, a versatile and scalable approach for ultrafast laser microfabrication of OECTs is herein reported, where a femtosecond laser to pattern insulating polymers (such as parylene C or polyimide) is first used, exposing the underlying metal electrodes serving as transistor terminals (source, drain, or gate). After the first patterning step, conducting polymers, such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), or semiconducting polymers, are spin-coated on the device surface. Another femtosecond laser patterning step subsequently defines the active polymer area contributing to the OECT performance by disconnecting the channel and gate from the surrounding spin-coated film. The effective OECT width can be defined with high resolution (down to 2 µm) in less than a second of exposure. Micropatterning the OECT channel area significantly improved the transistor switching performance in the case of PEDOT:PSS-based transistors, speeding up the devices by two orders of magnitude. The utility of this OECT manufacturing approach is demonstrated by fabricating complementary logic (inverters) and glucose biosensors, thereby showing its potential to accelerate OECT research.

The combination of flow elasticity and inertia has emerged as a viable tool for focusing and manipulating particles using microfluidics. Although there is considerable interest in the field of elasto-inertial microfluidics owing to its potential applications, research on particle focusing has been mostly limited to low Reynolds numbers (Re<1), and particle migration toward equilibrium positions has not been extensively examined. In this work, we thoroughly studied particle focusing on the dynamic range of flow rates and particle migration using straight microchannels with a single inlet high aspect ratio. We initially explored several parameters that had an impact on particle focusing, such as the particle size, channel dimensions, concentration of viscoelastic fluid, and flow rate. Our experimental work covered a wide range of dimensionless numbers (0.05 < Reynolds number < 85, 1.5 < Weissenberg number < 3800, 5 < Elasticity number < 470) using 3, 5, 7, and 10 µm particles. Our results showed that the particle size played a dominant role, and by tuning the parameters, particle focusing could be achieved at Reynolds numbers ranging from 0.2 (1 µL/min) to 85 (250 µL/min). Furthermore, we numerically and experimentally studied particle migration and reported differential particle migration for high-resolution separations of 5 µm, 7 µm and 10 µm particles in a sheathless flow at a throughput of 150 µL/min. Our work elucidates the complex particle transport in elasto-inertial flows and has great potential for the development of high-throughput and high-resolution particle separation for biomedical and environmental applications. (Figure presented.)

Life Cycle Assessment (LCA) is a well-known methodology used to calculate the environmental impacts of a product across its life cycle. The industrial machines used to manufacture consumer products are generally heavy, bulky, and have a complex product structure which makes their environmental assessment using LCA difficult as well as time and resource-intensive. Few studies have conducted LCA of complex industrial machines. The paper presents an LCA of a jet printing and dispensing machine (MY700), an industrial machine used in the production of printed circuit boards (PCBs) carried out using ReCiPe 2016 (Hierarchist) impact assessment methodology. In this study, the use phase of the machine accounted for 91% of the total environmental impacts. The compressed air and electricity consumed in the use phase of the machine were the major environmental hotspots. Additionally, some measures to minimize energy and compressed air use are also discussed. The methodology proposed in this article can be adopted by practitioners to conduct LCA of other industrial machines. The results of this study can help the machine manufacturers to undertake relevant eco-design activities as well as a comparison of different versions/machines in the product family for their environmental impact.

Stretchable electronics is a new innovation and becoming popular in various fields, especially in the healthcare sector. Since stretchable electronics use less printed circuit boards (PCBs), it is expected that the environmental performance of a stretchable electronics-based device is better than a rigid electronics-based device that provides the same functionalities. Yet, such a study is rarely available. Thus, the main purpose of this research is to perform a comparative life cycle analysis of stretchable and rigid electronics-based devices. This research combines both the case study approach and the research review approach. For the case study, a cardiac monitoring device with both stretchable and rigid electronics is used. The ISO 14044:2006 standard's prescribed LCA approach and ReCiPe 2016 Midpoint (Hierarchist) are followed for the impact assessment using the SimaPro 9.1 software. The LCA results show that the stretchable cardiac monitoring device has better environmental performance in all eighteen impact categories. This research also shows that the manufacturing process of stretchable electronics has lower environmental impacts than those for rigid electronics. The main reasons for the improved environmental performance of stretchable electronics are lower consumption of raw material as well as decreased energy consumption during manufacturing. Based on the LCA results of a cardiac monitoring device, the study concludes that stretchable electronics and their manufacturing process have better environmental performance in comparison with the rigid electronics and their manufacturing process.

Improved sample preparation has the potential to address unmet needs for fast turnaroundsepsis tests. In this work, we report elasto-inertial based rapid bacteria separation from diluted blood at high separation efficiency. In viscoelastic flows, we demonstrate novel findings where blood cells prepositioned at the outer wall entering a spiral device remain fullyfocused throughout the channel length while smaller bacteria migrate to the opposite wall.Initially, using microparticles, we show that particles above a certain size cut-off remainfully focused at the outer wall while smaller particles differentially migrate toward the inner wall. We demonstrate particle separation at 1 μm resolution at a total throughput of1 mL/min. For blood-based experiments, a minimum of 1:2 dilution was necessary to fullyfocus blood cells at the outer wall. Finally, Escherichia coli spiked in diluted blood were continuously separated at a total flow rate of 1 mL/min, with efficiencies between 82 and 90%depending on the blood dilution. Using a single spiral, it takes 40 min to process 1 mLof blood at a separation efficiency of 82%. The label-free, passive, and rapid bacteria isolation method has a great potential for speeding up downstream phenotypic and genotypicanalysis.

Passive particle manipulation using inertial and elasto-inertial microfluidics have received substantial interest in recent years and have found various applications in high throughput particle sorting and separation. For separation applications, elasto-inertial microfluidics has thus far been applied at substantial lower flow rates as compared to inertial microfluidics. In this work, we explore viscoelastic particle focusing and separation in spiral channels at two orders of magnitude higher Reynolds numbers than previously reported. We show that the balance between dominant inertial lift force, dean drag force and elastic force enables stable 3D particle focusing at dynamically high Reynolds numbers. Using a two-turn spiral, we show that particles, initially pinched towards the inner wall using an elasticity enhancer, PEO (polyethylene oxide), as sheath migrate towards the outer wall strictly based on size and can be effectively separated with high precision. As a proof of principle for high resolution particle separation, 15 mu m particles were effectively separated from 10 mu m particles. A separation efficiency of 98% for the 10 mu m and 97% for the 15 mu m particles was achieved. Furthermore, we demonstrate sheath-less, high throughput, separation using a novel integrated two-spiral device and achieved a separation efficiency of 89% for the 10 mu m and 99% for the 15 mu m particles at a sample flow rate of 1 mL/min-a throughput previously only reported for inertial microfluidics. We anticipate the ability to precisely control particles in 3D at extremely high flow rates will open up several applications, including the development of ultra-high throughput microflow cytometers and high-resolution separation of rare cells for point of care diagnostics.

When concentrated particle suspensions flow into a constricting channel, the suspended particles may either smoothly flow through the constriction or jam and clog the channel. These clogging events are typically detrimental to technological processes, such as in the printing of dense pastes or in filtration, but can also be exploited in micro-separation applications. Many studies have to date focused on important parameters influencing the occurrence of clogs, such as flow velocity, particle concentration, and channel geometry. However, the investigation of the role played by the particle surface properties has surprisingly received little attention so far. Here, we study the effect of surface roughness on the clogging of suspensions of silica particles under pressure-driven flows along a microchannel presenting a constriction. We synthesize micron-sized particles with uniform surface chemistry and tunable roughness and determine the occurrence of clogging events as a function of velocity and volume fraction for a given surface topography. Our results show that there is a clear correlation between surface roughness and flow rate, indicating that rougher particles are more likely to jam at the constriction for slower flows. These findings identify surface roughness as an essential parameter to consider in the formulation of particulate suspensions for applications where clogging plays an important role. 

Purpose The purpose of this study is to propose a novel simulation framework and show that it captures the main effects of the deposition process, such as droplet shape, volume and speed. Design/methodology/approach In the framework, the time-dependent flow and the fluid-structure interaction between the suspension, the moving piston and the deflection of the jetting head is simulated. The system is modelled as a two-phase system with the surrounding air being one phase and the dense suspension the other. The non-Newtonian suspension is modelled as a mixed single phase with properties determined from material testing. The simulations were performed with two coupled in-house solvers developed at Fraunhofer-Chalmers Centre; IBOFlow, a multiphase flow solver; and LaStFEM, a large strain FEM solver. Experimental deposition was performed with a commercial jet printer and quantitative measurements were made with optical profilometry. Findings Jetting behaviour was shown to be affected by not only piston motion, fluid rheology and head deformation but also the viscous energy loss in the jetting head nozzle. The simulation results were compared to experimental data obtained from an industrial jetting head and found to match characteristic lengths, speed and volume within ca 10%. Research limitations/implications The simulations are based on a rheological description using the Carreau model that does not include a time-dependent relaxation of the fluid. This modelling approach limits the descriptive nature of the deposit after impact on the substrate. The simulation also adopts a continuum approach to the suspension, which will not accurately model the break-off of the droplet filament under the characteristic diameter of the particles in the suspension. Practical implications The ability to accurately simulate the deposition of functional materials will enable the efficient development of novel product designs with a minimum of used resources and minimised product development duration. Social implications The ability to accurately simulate the deposition of functional materials will enable the efficient development of novel product designs with a minimum of used resources and therefore an improvement from a sustainability perspective. The ability to plan deposition strategies virtually will also enable a decrease in consumables at manufacturers which will in turn decrease their carbon foot print. Originality/value While basic fluid dynamic simulations have been performed to simulate flow through nozzles, the ability to include both fluid-structure interaction and multiphase capability together with a more accurate rheological description of the suspension and with a substrate for surface mount applications has not been published to the knowledge of the authors.