Table 3.

Overview of integrated systems for bottom-up methods.

NPs Type	Enabling Technologies/Modules	Crucial Parameters	NP Size (nm)	Costs 1	Year	Reference
CdSe	Continuous-microflow synthesis High-pressure microreactor	Solvent phase Concentration Temperature Residence time	~3–6	★★★★	2008	Marre [94]
CdSe	Combinational microreactors	Temperature Reaction time Reaction additive concentration	~2–4.5	★★★★	2010	Toyota [95]
CdTe, CdSe, alloy CdSeTe	Multichannel droplet reactor			★★★★	2013	Nightingale [91]
InP/ZnSeS	Millifluidic reactor system	Flow rate Reactor temperature Shell precursor concentration	5.9 ± 1.2	★★★	2018	Vikram [96]
PbS	Droplet-based microfluidic	Temperature Flow rate	2–6	★★	2015	Lignos [97]
Au	Millifluidic benchtop reactor system “Y” mixer Flow synthesis	Concentration	~2–40	★★★	2013	Lohse [100]
Au	Zigzag micromixer	Seeds volume Residence channel length	75 ± 6	★★★	2017	Thiele [117]
Au, bimetallic AuPd	Millifluidics Continuous flow	Flow rate Reactor geometry	6.4 ± 1.5 (I-shape connection)/6.3 ± 1.3 (helical reactor)	★★	2019	Cattaneo [102]
Ag	Droplet-based microfluidic reactor	Static mixing Temperature Flow rate	4.37–11.45	★★★	2018	Kwak [104]
Ag	Drop-based microfluidics	Concentration ratios Flow rates	4.9 ± 1.2	★★	2016	Xu [118]
Nobel metal	Millilitre-sized droplet reactors	Capping agent Reductant Reaction temperature	~9–50	★★★	2014	Zhang [101]
Nobel metal	Multichannel droplet reactor	Capping agent Reductant Reaction temperature	~2.5	★★★	2018	Niu [105]
Pd-Pt, Pd@Au (core@shell)	Duo-microreactor	Concentration	18.0 ± 2.7	★★★★	2019	Santana [119]
BaSO4, Au, CaCO3	Segmented flow microchannel Passive picoinjection	Injection volume	30–40 (BaSO4) 32–91 (Au)	★★★★	2018	Du [120]
Superparamagnetic iron oxide	Micellar electrospray		36 ± 6	★★★★	2014	Duong [121]
Ni	Continuous flow microreactor	Flow rates	~6.43–8.76	★★★	2015	Xu [122]
Fe3O4	Flow synthesis “T” mixer	Linear velocity Residence time Reactor dimension	4.9 ± 0.7	★★	2015	Jiao [123]
PLGA@HF, PLGA@AcDX	Multiplex microfluidics	Flow rates	~60–550	★★	2017	Liu [108]
PLGA	Microfluidic origami chip	Flow rates	~100	★★	2013	Sun [106]
PLGA, hydrophobic chitosan, acetylated dextran	3D coaxial flows Glass capillaries		~100–400	★★★	2015	Liu [107]
Metal-organic frameworks (MIL-88B)	Nanolitre continuous reactor Segmented flow	Residence time Temperature Volume slug	90–900	★★★	2013	Paseta [124]
Silica, polymersomes, niosomes	Microreaction technology	Flow rates	238–361 (silica)/275–75 (niosomes)	★★★	2019	Bomhard [125]
Ag	Liquid flame spray	Passing times	~10–100	★★★	2017	Brobbey [92]
SnO2	Single droplet combustion Flame spray pyrolysis	Metal-precursor concentration	~3–39	★★★★	2020	Li [112]
α-Al2O3	Flame synthesis	Ratios of oxygen and acetyl	50–150	★★★	2014	Kathirvel [114]
Cs0.32WO3	Flame-assisted spray pyrolysis	Flame temperature Flow rate	~6–300	★★★	2018	Hirano [116]
Fe/Al2O3	Flame spray pyrolysis	Precursor molar ratio Multicomponent structures	183–187	★★★	2016	Hafshejani [115]
Carbon	Flame synthesis Conical chimney	Combustion regime	~200	★★★	2016	Esmeryan [113]
Carbon nanotube	Flame synthesis Methane diffusion flames	Sampling time Sampling height Sampling substrate	30–110	★★★	2018	Chu [111]
Onion-like carbon	“Wick-and-oil” flame synthesis		~25 ± 5	★★★	2016	Mohapatra [93]

¹ The number of asterisks (★) represents the cost of synthesis system; 1 means relatively low cost, while 5 means expensive.