A lab-on-a-disc system enables 90 precise and reproducible nanoparticle syntheses in minutes by automatically controlling reagent concentrations across parallel reactions with minimal manual input.
(Nanowerk Spotlight) Creating a library of nanoparticles with slightly different shapes or sizes usually means preparing dozens of separate reaction tubes, measuring reagents by hand, and repeating mixing steps under carefully controlled conditions. It is labor intensive, time consuming, and often inconsistent, especially when reactions are sensitive to timing or concentration gradients. Small errors in pipetting or mixing can lead to large variations in particle structure or function, slowing progress in materials discovery and screening.
Researchers have been trying to solve this bottleneck by miniaturizing synthesis workflows. Microfluidic systems offer fine control over fluid volumes and reaction timing, but most require complex infrastructure such as external pumps, tubing, or customized chips. They are also poorly suited to performing many reactions in parallel. High throughput screening methods exist, but they often demand significant manual input or specialized equipment and remain difficult to scale.
Centrifugal microfluidics offers a more accessible approach. These systems use rotation to generate pressure, allowing precise fluid control without external pumps. Until now, however, their use has focused mainly on diagnostics and sample preparation rather than chemical synthesis.
The device, called DC UltraScreen 90, is a disc shaped cartridge with two layers of chambers and channels. It operates using a simple principle. When spun, centrifugal force pushes liquid from larger reservoirs into dozens of smaller reaction chambers. The device uses a siphon based design to precisely control when and how much each chamber fills. This mechanism prevents premature flow, enabling accurate volume delivery across all 90 reaction units in a single spin.
Operation of the DC-UltraScreen-90 microchip. a) Schematic representation of the simultaneous solution loading and aliquoting process for 90 reactions. b) Digital images illustrating the operational workflow of the DC-UltraScreen-90 microchip. c) Detail of the dual-gradient structure, showcasing the adjustment of HA and NaCt concentrations through the integration of the diluent layer (top) and reactant layer (bottom). d,e) Zoomedin views of (c), highlighting the precise aliquoting mechanism and the resulting concentration gradients after the mixing of all reactants with the diluent. f) Optimization of rotational speed for mixing solutions in reaction chambers. (Image: Reprinted from DOI:10.1002/adfm.202512734, CC BY) (click on image to enlarge)
Each of the six input reservoirs contains either a reactant or a diluent. These feed into a network of microchannels. A first high speed spin at 4000 revolutions per minute loads each chamber with precise aliquots. Then, a second lower speed spin at 2000 revolutions per minute mixes the contents gently, initiating reactions without disturbing the particle formation process. This two stage operation ensures uniformity across reactions and avoids early aggregation or precipitation that can affect reaction quality.
The most notable feature is the dual gradient system. Instead of using fixed concentrations, the device varies the amount of key reagents across the reaction array. Two of the six inputs, ascorbic acid and sodium citrate, are delivered in stepped gradients across 10 and 9 levels respectively. This creates 90 different combinations of reagent concentrations, allowing researchers to study how small shifts in formulation influence particle morphology.
To demonstrate the platform’s capabilities, the team used it to synthesize silver nanoparticles. At low concentrations of both ascorbic acid and sodium citrate, the particles formed as simple spheres. As the concentration of ascorbic acid increased, particles began to elongate and develop spikes. When both inputs were high, the result was the formation of silver nanostars, complex branched particles with useful optical and catalytic properties. These trends were reproducible across multiple runs, confirming the system’s reliability.
One of the platform’s key strengths is its ability to bridge microfluidic screening with traditional batch synthesis. To test scalability, the researchers repeated selected reactions in larger volumes using standard lab equipment. The resulting particles matched those produced on disc in shape, color, and optical characteristics. Reaction kinetics on the disc were slightly faster, likely due to higher mixing efficiency in small volumes, but the end results remained consistent.
Because it requires only six pipetting steps and no post processing, the platform significantly reduces user effort compared to traditional methods. Each printed disc costs less than five dollars, and the entire system including the motor and power source can be assembled for under two hundred. This low cost, low footprint setup makes the platform accessible to labs that lack advanced automation or synthesis infrastructure.
The system also supports different operating modes. In addition to performing all reactions simultaneously, it can be configured for sequential loading or time staggered reactions. That flexibility could make it useful for studying multistep processes or time dependent reactions.
The study does not suggest that the platform is universally applicable to all chemical synthesis. It is best suited for liquid phase reactions under ambient conditions and is designed primarily for screening rather than high volume production. Reactions requiring heat, inert atmospheres, or complex multistep pathways may need further development. However, the architecture is adaptable. Other reagents, gradient profiles, or reaction formats could be supported by adjusting input solutions and chamber layouts.
DC UltraScreen 90 directly addresses a central challenge in nanomaterials research, which is the difficulty of mapping chemical space quickly and reliably. By combining the precision of microfluidics with the simplicity of centrifugal operation, it enables rapid synthesis with fine control and low user burden. The ability to test how formulation changes affect particle morphology under tightly controlled conditions is essential for advancing nanoscale material discovery.
This work demonstrates that microfluidic systems, when carefully designed, can extend beyond diagnostics and sample handling into active roles in materials fabrication. The platform offers a low barrier, reproducible, and scalable solution for researchers working on nanoparticle synthesis, catalysis, and related applications.
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