Nanocrystal synthesis in microfluidic reactors: where next?

Abstract

The past decade has seen a steady rise in the use of microfluidic reactors for nanocrystal synthesis, with numerous studies reporting improved reaction control relative to conventional batch chemistry. However, flow synthesis procedures continue to lag behind batch methods in terms of chemical sophistication and the range of accessible materials, with most reports having involved simple one- or two-step chemical procedures directly adapted from proven batch protocols. Here we examine the current status of microscale methods for nanocrystal synthesis, and consider what role microreactors might ultimately play in laboratory-scale research and industrial production.

A reproducible approach to the assembly of microcapillaries for double emulsion production

“…Droplet microfluidics in particular has enabled new modes for cell sorting and analysis (Eun et al 2011;Mazutis et al 2013;Zhang et al 2013), single molecule immunoassays (Shim et al 2013), directing biomolecule evolution (Agresti et al 2010;Kintses et al 2012), and the synthesis of crystals Phillips et al 2014;Yashina et al 2012), contrast agents (Abbaspourrad et al 2013), and drug delivery particles (Leon et al 2014;Xu et al 2009)-among other advances (Casadevall i Solvas and deMello 2011; Guo et al 2012;Song et al 2006;Teh et al 2008;Theberge et al 2010). However, in spite of the great potential of microfluidics (Whitesides 2006), these devices are still not routinely used by non-specialists, due in part to the demands of device fabrication and the almost inevitable need to trouble-shoot (Whitesides 2013;Yetisen et al 2013).…”

Controlled microdroplet transport in an atmospheric pressure microplasma

“…3 However, injecting and controlling isolated droplets within a non-thermal plasma would offer opportunities for fundamental studies and modelling of the complex electron-liquid non-equilibrium chemistry. 4 It also opens up the prospects of technological applications, such as gasphase microreactors, which while analogous to their microfluidic counterparts with multiphase emulsion flows, [5][6][7] plasma-liquid systems offer additional chemistries, materials, and a route to large scale implementation. 3,8 In plasma medicine, plasma activated droplets will also enhance the scope for remote delivery of therapeutic agents to biological tissue and organs.…”

Online detection and automation methods in microfluidic nanomaterial synthesis

“…The synthesis of such exceptional materials demands that critical parameters including reagent concentration, temperature and pressure be uniform throughout the reaction mixture; in turn allowing the formation of particles with nearly identical size, shape and chemical composition [4]. Such requirements are difficult to realize in macroscale reactors, due to inhomogeneous mixing and inefficient heat transfer [5,6 ]. Indeed, whilst conventional flaskbased reactors are often used to prepare nanoparticles in large quantities, they are not always successful in delivering nanoparticle populations of consistent size and size distribution [6 ].…”

“…Such requirements are difficult to realize in macroscale reactors, due to inhomogeneous mixing and inefficient heat transfer [5,6 ]. Indeed, whilst conventional flaskbased reactors are often used to prepare nanoparticles in large quantities, they are not always successful in delivering nanoparticle populations of consistent size and size distribution [6 ].…”