Modular and Integrated Systems for Nanoparticle and Microparticle Synthesis-A Review

Abstract

Nanoparticles (NPs) and microparticles (MPs) have been widely used in different areas of research such as materials science, energy, and biotechnology. On-demand synthesis of NPs and MPs with desired chemical and physical properties is essential for different applications. However, most of the conventional methods for producing NPs/MPs require bulky and expensive equipment, which occupies large space and generally need complex operation with dedicated expertise and labour. These limitations hinder inexperienced researchers to harness the advantages of NPs and MPs in their fields of research. When problems individual researchers accumulate, the overall interdisciplinary innovations for unleashing a wider range of directions are undermined. In recent years, modular and integrated systems are developed for resolving the ongoing dilemma. In this review, we focus on the development of modular and integrated systems that assist the production of NPs and MPs. We categorise these systems into two major groups: systems for the synthesis of (1) NPs and (2) MPs; systems for producing NPs are further divided into two sections based on top-down and bottom-up approaches. The mechanisms of each synthesis method are explained, and the properties of produced NPs/MPs are compared. Finally, we discuss existing challenges and outline the potentials for the development of modular and integrated systems.

Keywords: integrated systems; microfluidics; microparticles; modularisation; nanoparticles; synthesis.

Figure 11

Illustrations of jetting mechanism and jetting systems. (A) Schematic of a typical jetting platform. (B) Schematic diagram of the piezoelectric membrane-piston-based jetting technology (PMPJT) system. (C) The principle of microdroplet formation based on the PMPJT. Reprinted with permission from ref [160]. (D) Schematic illustration of the aluminium (Al) microdroplets generation system combining supersonic laser-induced jetting and velocity measuring function. PD represents photodiode and LS is laser system. Reprinted with permission from ref [161].

Figure 1

Scheme of top-down and bottom-up synthesis of nanoparticles (NPs).

Figure 2

Schematics of ultrasonic mechanism and representative platforms. (A) Schematic of sonication mechanism. (B) Exploded schematic of the liquid metal (LM) NP production platform with a dynamic temperature control system. Reprinted with permission from ref [54]. Copyright (2020) American Chemical Society. (C) Experimental setup of the on-chip LM NP production platform. Reprinted with permission from ref [51]. (D) Exploded schematic of a liquid-based nebulization system. Reprinted with permission from ref [55]. (E) The schematic of the mechanism for producing EGaIn LM NPs.

Figure 3

Schematic of laser ablation systems for producing NPs. (A) Schematic representation of a typical setup for liquid phase laser ablation. (B) An ultrasonic-assisted pulse laser ablation (PLA) system. Reprinted with permission from ref [59]. (C) Illustration of magnetic field assisted laser ablation system. Reprinted with permission from ref [60]. (D) Schematic showing the laser ablation in liquid setup. A laser beam is deflected by two scanning systems: a polygon scanner for the vertical axis and a galvanometric mirror for the horizontal axis. Reprinted with permission from ref [61] © The Optical Society.

Figure 4

Microfluidic/millifluidic systems for producing NPs. (A) microfluidic system for producing CdSe quantum dots (QDs). Reprinted with permission from ref [94]. (B) A combinatorial synthesis system contains several microreactors for CdSe NPs production [95]. (C) A multichannel droplet microfluidic reactor. Reprinted with permission from ref [91].

Figure 5

Schematic of modular microfluidic systems for producing NPs. (A) A droplet-reactor system with the potential for automation. Reprinted with permission from ref [105]. (B) A microfluidic origami chip with different configurations for enhancing mixing. Reprinted with permission from ref [106].

Figure 6

Flame synthesis systems for producing NPs. (A) Schematic representation of a typical flame synthesis system. (B) Schematic of methane coaxial jet diffusion flam system. Reprinted with permission from ref [111]. (C) Experimental setup for single isolated droplet combustion. Reprinted with permission from ref [112]. (D) The setup and schematic of the liquid flame spray (LFS) system. Reprinted with permission from ref [92].

Figure 7

Microfluidic systems for producing microparticles (MPs). (A) Schematic view of a magnetically driven microfluidic droplet generation technique using ferrofluids (without any pumps). (B) Top and front views of the microfluidic device with dimensions. Reprinted with permission from ref [130]. (C) Overview of multidimensional scale-up strategy (not to scale). Reprinted with permission from ref [134].

Figure 8

Microfluidic systems applying 3D printing technology. (A) Setup of a 3D-printed screw-and-nut droplet generator, the schematic also illustrates the control of the droplet size. Reprinted with permission from ref [147]. (B) Virtual object photographs of the 3D-printed millifluidic device with two inlets for continuous and dispersed phase and one outlet. Reprinted with permission from ref [148]. (C) Real image of the four-parallelised-chimneys device with the same apex angle. Scale bar is 2 cm.

Figure 9

Schematics of acoustic systems for MPs production. (A) Schematic of a droplet generation system incorporating an ultrasonic torsional transducer and a micropore plate. Reprinted with permission from ref [150]. (B) Exploded schematic of the acoustic-based LM microdroplet production platform. The inset is the assembled view. Reprinted with permission from ref [48].

Figure 10

Schematics of centrifugal and spinning systems. (A) Illustration of the centrifuge-based axisymmetric coflowing microfluidic device. Reprinted with permission from ref [154]. (B) Components and schematic of the centrifuge-based step emulsion device. Reprinted with permission from ref [155]. (C) Schematic illustration of the liquid emulsion generator and process of droplet formation. Reprinted with permission from ref [49]. (D) Schematic representation of the off-chip spinning microdroplet generator. Reprinted with permission from ref [129].