This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(Ministry of Science and ICT). (No. NRF-2021R1A2C1011380).

1. Designing the microfluidic platform for particle concentration
<ol>
	<li>Design the pneumatic microfluidic platform consisting of one pneumatic valve for fluid flow in the 3D flow network and three pneumatic valves for sieve (Vs), fluid (Vf), and particle (Vp) valve operation (Figure 1). 
	NOTE: Vs blocks concentrate particles from the liquid, and Vf and Vp allow fluid and particle release after concentration. Three pneumatic ports provide compressed air from the fluid/pneumatic supply layer (normally open) and the pneumatic valve light outlet to actuate the valve. The microfluidic channel network is designed with a CAD program18,19.</li>
	<li>Design the channel to be a pneumatic supply layer and a 3D channel network layer (Figure 2). 
	NOTE: The fluid network is interconnected with the curved channels in the anterior part and the rectangular chamber in the posterior region. Vs block the inlet, and particles accumulate in the collection area of the curved fluid channel. Particle-free fluids (particle-free liquids) are exited through the Qf outlet and the concentrated particles through the Qp outlet (Figure 3).</li>
	<li>According to the above conditions, prepare four types of SU-8 molds. 
	NOTE: The four molds include a mold that allows the valve to be controlled via pneumatics, two molds that create fluid channels, and a clean mold without shape (Figure 4 and Table 1). The four types of molds mentioned are fabricated using standard photolithography processes. This mold making consists of a SU-8 mold on a silicon wafer as per previously published reports18,19. Figure 5 depicts the device chip.</li>
</ol>
2. Fabrication of the microfluidic platform for particle concentration
NOTE: Figure 6 illustrates the fabrication of a microfluidic platform that concentrates particles.
<ol>
	<li>Replicate the PDMS layer using a prepared pneumatic valve channel SU-8 mold (step 1.3) for pneumatically controlling the valve.
	<ol>
		<li>Pour 10 mL of liquid PDMS and 1 mL of curing agent (see Table of Materials) into a prepared pneumatic valve channel mold (step 1.3) and heat-activate at 90 &#176;C for 30 min.</li>
		<li>After the PDMS structures are cured, separate the SU-8 mold of step 2.1.1.</li>
		<li>Punch three 1.5 mm pneumatic ports (Vs, Vf, and Vp) into the pneumatic valve channel manufactured according to step 2.1.2 using a 1.5 mm puncture (see Table of Materials).</li>
		<li>Pour 10 mL of liquid PDMS and 1 mL of curing agent into a prepared clean SU-8 mold prepared in step 1.3 and spin-coat at 1,500 rpm for 15 s using a spin coater (see Table of Materials). Then heat-activate at 90 &#176;C for 30 min.</li>
		<li>After the PDMS structures are cured, separate the SU-8 mold of step 2.1.4. 
		NOTE: The valve diaphragm layer controls fluid flow according to the pneumatic pressure.</li>
		<li>Treat atmospheric plasma (see Table of Materials) to the PDMS structures prepared in steps 2.1.3 and 2.1.5 for 20 s.</li>
		<li>Align directly plasma-treated PDMS structures from step 2.1.6 according to the channel structure by checking with a microscope.</li>
		<li>Bond the aligned PDMS structures prepared in step 2.1.7 by heating at 90 &#176;C for 30 min.</li>
		<li>Punch a 1.5 mm diameter hole in the fluid channel inlet (Qfp) and fluid channel outlets (Qf and Qp) within the pneumatic channel part to which the thin diaphragm layer is bonded, using a 1.5 mm puncture.</li>
	</ol>
	</li>
	<li>Replicate both sides of the PDMS layer using two SU-8 molds to make a microfluidic channel. Use a curved and rectangular microfluidic channel mold on the front and a microfluidic interconnection channel mold on the rear.
	<ol>
		<li>Pour 10 mL of liquid PDMS and 1 mL of curing agent into the curved and rectangular microfluidic channel mold and spin-coat at 1,200 rpm for 15 s. Then create molds for the curved fluid chamber and fluid channels by thermal activation at 90 &#176;C for 30 min (Figure 6A).</li>
		<li>Separate the PDMS layer on which the microfluidic channel is formed, then make a heat-activated mold covering the sealed vent wall by bonding to the glass wafer by treating atmospheric plasma for 20 s (Figure 6B).</li>
		<li>Pour 3 mL of liquid PDMS into the interconnection channel of the SU-8 mold (Figure 6C).</li>
		<li>Arrange the structure fabricated in step 2.2.2 with the interconnection channel mold in liquid PDMS on the microfluidic interconnect channel mold, and dry the superimposed structure at 130 &#176;C for 30 min (Figure 6D). 
		NOTE: While curing the rear structure, the PDMS mold fabricated in step 2.2.2 is inflated by the thermal pressure of the air layer, and the deformed PDMS layer is thermally activated (Figure 6E)16.</li>
		<li>After curing, remove the front SU-8 mold from the microfluidic channel network layer and carefully peel off the rear PDMS mold (Figure 6F). 
		NOTE: The 3D fluidic network layer allows the creation of an anterior curved fluid chamber and microfluidic channels.</li>
		<li>Pour 10 mL of liquid PDMS and 1 mL of curing agent into a clean SU-8 mold. Then heat-activate at 90 &#176;C for 30 min.</li>
		<li>After the PDMS structures are cured, separate the SU-8 mold. 
		NOTE: This step creates the additional sealing layer.</li>
		<li>Treat the atmospheric plasma to PDMS structures prepared in steps 2.2.3 and 2.2.7 for 20 s.</li>
		<li>Align directly plasma-treated PDMS structures according to the channel structure by checking with a microscope.</li>
		<li>Bond the aligned PDMS structures by heating at 90 &#176;C for 30 min.</li>
	</ol>
	</li>
	<li>Align the PDMS structures prepared in steps 2.1 and 2.2 according to the channel structure and bond them by treating atmospheric plasma for 20 s.</li>
</ol>
3. Setting up the device
NOTE: Figure 7 shows fabricating a microfluidic platform that concentrates particles.
<ol>
	<li>Manually fill the microfluidic channel with bubble-free demineralized water using a 10 mL syringe.</li>
	<li>To control the P_Qfp and the three pneumatic valves (P_Vs, P_Vf, and P_Vp) that control the microbead flow, insert a precision pressure controller with four or more output channels (see Table of Materials) for the working fluid (Qfp) into the microfluidic platform. 
	NOTE: A precision pressure controller with four output channels can be replaced with multiple precision pressure controllers. In this experiment, the operating pressure of P_Qfp was 10 kPa, P_Vs was 15 kPa, and P_Vf and P_Vp were both 18 kPa (Figure 8 and Table 2). Figure 8 shows the working fluid flow rate over time as particles are concentrated by the microfluidic platform with P_Vs of 15 kPa, and Table 2 shows the actuation results according to the pneumatic valves.</li>
	<li>Prepare carboxyl polystyrene test particles of various sizes in distilled water (see Table of Materials). 
	NOTE: The particle sizes used in this experiment were 24.9, 8.49, and 4.16 &#181;m; particles of various sizes can be used depending on the pressure of P_Vs.</li>
	<li>To control the flow rate of the working fluid, fill a glass bottle half full with water (working fluid) and connect the glass bottle cap to the controller output channel and microvalve. 
	NOTE: Connect one tube to the microvalve to receive compressed air from the controller and the other tube to inject water.</li>
	<li>Observe platform operation through an inverted microscope for all platform operations and measure the operating flow rate over time at the outlet by a liquid flow meter (see Table of Materials).</li>
</ol>
4. Operation of the device
<ol>
	<li>Inject the particle/fluid mixture under pressure at the inlet (Qfp) with Vp (Figure 9A). 
	NOTE: The flow of particles and clean fluid from the outlet through the interconnected channels are controlled via Vp and Vf, respectively (Table 2).</li>
	<li>Apply pressure to Vs at 15 kPa and Vp at 18 kPa to actuate the valve. 
	NOTE: At this time, the diaphragm is deformed, the particles of the fluid Qfp are blocked in the contact space between the curved fluid channel and the curved fluid cantilever, and the unwanted Qfp fluid is released through the open Qf (Figure 9B,C).</li>
	<li>When the particles are concentrated, apply pressure only to Vf. 
	NOTE: At this time, when pressure is applied only to Vf, the clogged particles are released through Qp (Figure 9D).</li>
</ol>

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The authors have no conflicts of interest to disclose.

This platform provides a simple way to purify and concentrate particles of various sizes. Particles are accumulated and released through pneumatic valve control, and no clogging is observed because there is no passive structure. Using this device, the concentration of particles of three sizes is presented. However, the operating pressure, the time required for concentration, and the rate may vary depending on the device dimensions, particle size magnification, and the pressure at Vs18,<...

Due to the importance of biological analysis, microfluidic and biomedical microelectromechanical systems (BioMEMS) technologies1,2 are used to develop and study devices for the purification and collection of micromaterials2,3,4.&#160;Particle capture is categorized as active or passive. Active traps have been used for external dielectric5, magnetophoretic6, auditory7, visual8, or thermal9 forces acting on independent particles, enabling precise control of their movements. However, an interaction between the particle and external force is required; thus, the throughput is low. In microfluidic systems, controlling the flow rate is very important because the external forces are transmitted to the target particles.
In general, passive microfluidic devices have micropillars in microchannels10,11. Particles are filtered through interaction with a flowing fluid, and these devices are easy to design and inexpensive to manufacture. However, they cause particle clogging in micro-pillars, so more complex devices have been developed to prevent particle clogging12. Microfluidic devices with complex structures are generally suitable for managing a limited number of particles13,14,15,16,17,18.
This article describes a method to fabricate and operate a pneumatically driven microfluidic platform for large particle concentrations that overcomes the shortcomings18 as mentioned above. This platform can block and concentrate particles by deformation and actuation of the thin diaphragm layer of the sieve valve (Vs) plate that accumulates in curved microfluidic channels. Particles accumulate in curved microfluidic channels, and the concentrated particles can separate by discharging the working fluid via the actuation of two PDMS seals on/off valves18. This method makes it possible to process a limited number of particles or concentrate a large number of small particles. Operating conditions such as the magnitude of flow rate and compressed air pressure can prevent unwanted cell damage and increase cell trapping efficiency.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1.5 mm puncture</td>
			<td>Self procduction</td>
			<td>Self procduction</td>
			<td>This puncture was made by requesting a mold maker based on the Miltex&#174; Biopsy Punch with Plunger (15110-15) product.</td>
		</tr>
		<tr>
			<td>4 inch Silicon Wafer/SU-8 mold</td>
			<td>4science</td>
			<td>29-03573-01</td>
			<td>4 inch (100) Ptype silicon wafer/SU-8 mold</td>
		</tr>
		<tr>
			<td>Carboxyl Polystyrene Crosslinked Particle(24.9 &#956;m)</td>
			<td>Spherotech</td>
			<td>CPX-200-10</td>
			<td>Concentrated bead sample1</td>
		</tr>
		<tr>
			<td>Flow meter</td>
			<td>Sensirion</td>
			<td>SLI-1000</td>
			<td>Flow measurement</td>
		</tr>
		<tr>
			<td>High-speed camera</td>
			<td>Photron</td>
			<td>FASTCAM Mini</td>
			<td>Observation of concentration</td>
		</tr>
		<tr>
			<td>Hot plate</td>
			<td>As one</td>
			<td>HI-1000</td>
			<td>heating plate for curing of liquid PDMS</td>
		</tr>
		<tr>
			<td>KOVAX-SYRINGE 10 mL/Syringe</td>
			<td>Koreavaccine</td>
			<td>22G-10ML</td>
			<td>Fill the microfluidic channel with bubble-free demineralized water.</td>
		</tr>
		<tr>
			<td>Laboratory Conona treater/Atmospheric plasma</td>
			<td>Electro-Technic</td>
			<td>BD-20AC</td>
			<td>Chip bonding/atmospheric plasma</td>
		</tr>
		<tr>
			<td>Liquid polydimethylsiloxane, PDMS</td>
			<td>Dow Corning Inc.</td>
			<td>Sylgard 184</td>
			<td>Components of chip</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>IX-81</td>
			<td>Observation of concentration</td>
		</tr>
		<tr>
			<td>PEEK Tubes</td>
			<td>SAINT-GOBAIN PPL CORP.</td>
			<td>AAD04103</td>
			<td>Inject or collect particles</td>
		</tr>
		<tr>
			<td>Polystyrene Particle(4.16 &#956;m)</td>
			<td>Spherotech</td>
			<td>PP-40-10</td>
			<td>Concentrated bead sample3</td>
		</tr>
		<tr>
			<td>Polystyrene Particle(8.49 &#956;m)</td>
			<td>Spherotech</td>
			<td>PP-100-10</td>
			<td>Concentrated bead sample2</td>
		</tr>
		<tr>
			<td>Pressure controller/&#956;flucon</td>
			<td>AMED</td>
			<td>&#956;flucon</td>
			<td>Control of air pressure</td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>iNexus</td>
			<td>ACE-200</td>
			<td>spread the liquid PDMS on SU-8 mold</td>
		</tr>
	</tbody>
</table>

pneumatically driven microfluidic platform for micro-particle concentration

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. This platform has a three-dimensional (3D) network with curved fluid channels and three pneumatic valves, which create networks, channels, and spaces through duplex replication with polydimethylsiloxane (PDMS). The device operates based on the transient response of a fluid flow rate controlled by a pneumatic valve in the following order: (1) sample loading, (2) sample blocking, (3) sample concentration, and (4) sample release. The particles are blocked by thin diaphragm layer deformation of the sieve valve (Vs) plate and accumulate in the curved microfluidic channel. The working fluid is discharged by the actuation of two on/off valves. As a result of the operation, all particles of various magnifications were successfully intercepted and disengaged. When this technology is applied, the operating pressure, the time required for concentration, and the concentration rate may vary depending on the device dimensions and particle size magnification.

Figure 8 shows the flow rate of the fluid rates for a four-stage platform operation, as mentioned in Table 2. The first stage is the loading state (a state). The platform was supplied with fluid with all valves open, and the working fluid (Qf) and particles (Qp) are almost identical as the microfluidic channel network exhibits structural symmetry. In the second stage (b state), compressed air was transported to Vs to block the particles, and as the Vs diaphragm deformed, the...

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Pneumatically Driven Microfluidic Platform for Micro-Particle Concentration

The present protocol describes a pneumatic microfluidic platform that can be used for efficient microparticle concentration.

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. ...

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Engineering

2.3K Views.  Inje University. The present protocol describes a pneumatic microfluidic platform that can be used for efficient microparticle concentration.

Video: Pneumatically Driven Microfluidic Platform for Micro-Particle Concentration

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Picoinjection of Microfluidic Drops Without Metal Electrodes

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of these electrodes adds cumbersome and error-prone steps to the device fabrication process. We have developed a technique that obviates the needs for metal electrodes during picoinjection. Instead, it uses the injection fluid itself as an electrode, since most biological reagents contain dissolved electrolytes and are conductive. By eliminating the electrodes, we reduce device fabrication time and complexity, and make the devices more robust. In addition, with our approach, the injection volume depends on the voltage applied to the picoinjection solution; this allows us to rapidly adjust the volume injected by modulating the applied voltage. We demonstrate that our technique is compatible with reagents incorporating common biological compounds, including buffers, enzymes, and nucleic acids.

We have developed a technique for picoinjecting microfluidic drops that does not require metal electrodes. As such, devices incorporating our technique are simpler to fabricate and to use.

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of ...

Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving imaging system, such as an airborne platform or satellite. The resolution improvement is obtained in a two-step process. First, three low resolution differently defocused images are being captured and the optical phase is retrieved using an improved iterative Gerchberg-Saxton based algorithm. The phase retrieval allows to numerically back propagate the field to the aperture plane. Second, the imaging system is shifted and the first step is repeated. The obtained optical fields at the aperture plane are combined and a synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution. The method resembles a well-known approach from the microwave regime called the Synthetic Aperture Radar (SAR) in which the antenna size is synthetically increased along the platform propagation direction. The proposed method is demonstrated through laboratory experiment.

A method for overcoming the optical diffraction limit is presented. The method includes a two-step process: optical phase retrieval using iterative Gerchberg-Saxton algorithm, and imaging system shifting followed by repetition of the first step. A synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution.

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including microresonators. However, because of the increased acoustic radiative losses during direct liquid immersion of optomechanical devices, almost all published optomechanical experiments have been performed in solid phase. This paper discusses a recently introduced hollow microfluidic optomechanical resonator. Detailed methodology is provided to fabricate these ultra-high-Q microfluidic resonators, perform optomechanical testing, and measure radiation pressure-driven breathing mode and SBS-driven whispering gallery mode parametric vibrations. By confining liquids inside the capillary resonator, high mechanical- and optical- quality factors are simultaneously maintained.

Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

Here, we present three protocols for thermal measurements in microfluidic devices.

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

A High Performance Impedance-based Platform for Evaporation Rate Detection

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was employed here for demonstration purposes. Multiple evaporation tests on the model compound as a humectant with various concentrations in solutions were conducted for comparison purposes. A conventional weight loss approach is known as the most straightforward, but time-consuming, measurement technique for evaporation rate detection. Yet, a clear disadvantage is that a large volume of sample is required and multiple sample tests cannot be conducted at the same time. For the first time in literature, an electrical impedance sensing chip is successfully applied to a real-time evaporation investigation in a time sharing, continuous and automatic manner. Moreover, as little as 0.5 ml of test samples is required in this impedance-based apparatus, and a large impedance variation is demonstrated among various dilute solutions. The proposed high-sensitivity and fast-response impedance sensing system is found to outperform a conventional weight loss approach in terms of evaporation rate detection.

This paper presents an impedance-based apparatus for evaporation rate detection of solutions. It offers clear advantages over a conventional weight loss approach: a fast response, high-sensitivity detection, a small sample requirement, multiple sample measurements, and easy disassembly for cleaning and reuse purposes.

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are a rapidly growing class of materials in commercial electronics, such as light emitting diodes (LEDs) and photovoltaics (PVs). Among this material group, inorganic/organic perovskites have demonstrated significant improvement and potential towards high-efficiency, low-cost PV fabrication due to their high charge carrier mobilities and lifetimes. Despite the opportunities for perovskite QDs in large-scale PV and LED applications, the lack of fundamental and comprehensive understanding of their growth pathways has inhibited their adaptation within continuous nanomanufacturing strategies. Traditional flask-based screening approaches are generally expensive, labor-intensive, and imprecise for effectively characterizing the broad parameter space and synthesis variety relevant to colloidal QD reactions. In this work, a fully autonomous microfluidic platform is developed to systematically study the large parameter space associated with the colloidal synthesis of nanocrystals in a continuous flow format. Through the application of a novel translating three-port flow cell and modular reactor extension units, the system may rapidly collect fluorescence and absorption spectra across reactor lengths ranging 3 - 196 cm. The adjustable reactor length not only decouples the residence time from the velocity-dependent mass transfer, it also substantially improves the sampling rates and chemical consumption due to the characterization of 40 unique spectra within a single equilibrated system. Sample rates may reach up to 30,000 unique spectra per day, and the conditions cover 4 orders of magnitude in residence times ranging 100 ms - 17 min. Further applications of this system would substantially improve the rate and precision of the material discovery and screening in future studies. Detailed within this report are the system materials and assembly protocols with a general description of the automated sampling software and offline data processing.

Detailed herein are the operation and assembly protocols of a modular microfluidic screening platform for the systematic characterization of colloidal semiconductor nanocrystal syntheses. Through fully adjustable system arrangements, highly efficient spectra collection may be carried out across 4 orders of magnitude reaction time scales within a mass transfer-controlled sampling space.

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are a rapidly growing class of materials in commercial electronics, such as light ...

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface between two different materials is necessary. The S-Sm junction with high interface transparency will then facilitate the observation of the induced hard superconducting gap, which is the key requirement to access the topological phases (TPs) and observation of exotic quasiparticles such as Majorana zero modes (MZM) in hybrid systems. A material platform that can support observation of TPs and allows the realization of complex and branched geometries is therefore highly demanding in quantum processing and computing science and technology. Here, we introduce a two-dimensional material system and study the proximity induced superconductivity in semiconducting two-dimensional electron gas (2DEG) that is the basis of a hybrid quantum integrated circuit (QIC). The 2DEG is a 30 nm thick In0.75Ga0.25As quantum well that is buried between two In0.75Al0.25As barriers in a heterostructure. Niobium (Nb) films are used as the superconducting electrodes to form Nb- In0.75Ga0.25As -Nb Josephson junctions (JJs) that are symmetric, planar and ballistic. Two different approaches were used to form the JJs and QICs. The long junctions were fabricated photolithographically, but e-beam lithography was used for short junctions&#8217; fabrication. The coherent quantum transport measurements as a function of temperature in the presence/absence of magnetic field B are discussed. In both device fabrication approaches, the proximity induced superconducting properties were observed in the In0.75Ga0.25As 2DEG. It was found that e-beam lithographically patterned JJs of shorter lengths result in observation of induced superconducting gap at much higher temperature ranges. The results that are reproducible and clean suggesting that the hybrid 2D JJs and QICs based on In0.75Ga0.25As quantum wells could be a promising material platform to realize the real complex and scalable electronic and photonic quantum circuitry and devices.

Quantum integrated circuits (QICs) consisting of array of planar and ballistic Josephson junctions (JJs) based on In0.75Ga0.25As two-dimensional electron gas (2DEG) is demonstrated. Two different methods for fabrication of the two-dimensional (2D) JJs and QICs are discussed followed by the demonstration of quantum transport measurements in sub-Kelvin temperatures.

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface ...