Risa Fujita

Laminar co-flow in microchannels typically results in stratified streams with diffusion-limited mixing. This work presents an additively manufactured microfluidic platform that integrates a pulse tank and a transverse injection nozzle into an otherwise straight channel, enabling pulse-driven mixing and droplet generation using air-pressure actuation alone. In Device A, transverse pulsed injection disrupted the stratified interface and significantly enhanced mixing compared with the no-pulse case, as confirmed by an entropy-based mixing index. In Device B, pulsed injection into a continuous oil phase enabled stable droplet-on-demand generation with pressure-tunable droplet diameter in a straight circular channel. The devices operated in a laminar regime, with representative Reynolds, Péclet, and capillary numbers confirming diffusion-limited baseline mixing and stable dripping-type droplet formation. The results demonstrate that pulse-driven injections in a simple, additively manufactured geometry provide an effective, low-complexity approach to mixing enhancement and droplet generation without external fields or complex channel designs.

Our ‘trap-and-harvest’ device integrates in situ solid formation in trapped droplets with transfer to a physically accessible chamber, facilitating the direct harvesting of solid precipitates from the microfluidic device.

Accurate temperature regulation is essential in microfluidic apparatus, particularly for procedures such as polymerase chain reaction (PCR), cellular analysis, and chemical reactions that rely on stable thermal conditions. However, achieving temperature uniformity at the microscale remains challenging due to rapid heat dissipation, small thermal mass, and intricate flow–heat interactions. This work reviews contemporary methodologies to enhance thermal control in microfluidic systems, including proportional–integral–derivative (PID) and fuzzy PID controllers, liquid metal-based sensing, thermoelectric cooling (TECs), and evaporation or integrated heating elements for precise thermal output management. Emerging fabrication technologies, such as additive manufacturing, enable the direct integration of heating elements and sensors within microchips, improving thermal efficiency and device compactness. Advanced materials, including carbon nanotubes infused with gallium and temperature-sensitive quantum dots, offer innovative, non-contact thermal monitoring capabilities. Furthermore, artificial intelligence-driven feedback systems present opportunities for adaptive, real-time thermal optimization. By consolidating these strategies, this review highlights pathways to develop more dependable, efficient, and application-ready microfluidic devices, with implications for diagnostics, research, and other practical uses.

Quantum dots with sizes between 1 and 100 nm possess unique optical and electronic properties, making them valuable in energy, bioimaging, and optoelectronics fields. While traditional synthesis methods offer control over QD properties, they face challenges in scalability and reproducibility. Integrating microfluidics addresses these issues, providing precise control and high-throughput capabilities. This review highlights the transition from PDMS-based devices to additive-manufactured microfluidics, emphasizing their ability to overcome limitations in traditional methods. These advancements smooth the way for scalable, cost-effective, and sustainable QD production with enhanced application potential.

In this study, we developed a comb-shaped microfluidic device that can efficiently trap and culture a single cell (bacterium). Conventional culture devices have difficulty in trapping a single bacterium and often use a centrifuge to push the bacterium into the channel. The device developed in this study can store bacteria in almost all growth channels using the flowing fluid. In addition, chemical replacement can be performed in a few seconds, making this device suitable for culture experiments with resistant bacteria. The storage efficiency of microbeads that mimic bacteria was significantly improved from 0.2% to 84%. We used simulations to investigate the pressure loss in the growth channel. The pressure in the growth channel of the conventional device was more than 1400 PaG, whereas that of the new device was less than 400 PaG. Our microfluidic device was easily fabricated by a soft microelectromechanical systems method. The device was highly versatile and can be applied to various bacteria, such as Salmonella enterica serovar Typhimurium and Staphylococcus aureus.

Cortical neurons die in necrosis in the low-density (LD) culture, and in apoptosis in the high-density (HD) culture under the serum-free condition without any supplements. The neuronal death in LD culture was delayed by conditioned medium (CM) factors prepared from the HD culture. The CM switched the cell death mode from necrosis to apoptosis, characterized by various cell death markers and transmission electron microscopy. The CM inhibited the rapid decrease in cellular ATP levels and [³H]-2-deoxy glucose ([³H]-2-DG) uptake in the LD culture. Inhibitors of phospholipase C and protein kinase C effectively abolished the CM-induced elevation of survival activity, [³H]-2-DG uptake and ATP levels, and necrosis–apoptosis switch. All these results suggest that CM caused the cell death mode switch from necrosis to apoptosis through phospholipase C- and protein kinase C-mediated mechanisms.