Microfluidics in Planar Microchannels: Synthesis of Chemical Compounds On-Chip

Abstract

Microreactors are a wide class of devices that are currently playing a prominent role in several research fields such as biology, medicine, food chemistry, environmental analysis, up to the production of compounds in organic chemistry. Several typologies of microreactors have been produced with tubular or planar shapes, of different materials and designs. In this chapter, an overview of planar microchannel-based microreactors and their application to organic chemistry is given. Initially, after recalling the main theoretical parameters of microfluidics, an introduction of the proposed technology and the main requirements to perform mixing, which is essential to perform chemical synthesis on-chip, is presented. Silicon and glass microreactors, the most common planar systems for organic chemistry, are described with the aim of pointing out the most important parameters to be taken into consideration in the planning of a specific microreactor to be used for mixing, purification or crystallization of chemicals at the microscale. Then, several applications of initially described microreactors to organic chemistry for research applications are given. In the next section, the use of planar microchannel microreactors in the field of radiochemistry is reported. The radiopharmaceutical application is not casual, being a sector in which the microreactor technology is very promising, due to the need of quickly producing small and fresh amounts of products in a controlled environment. Finally, for completeness, other approaches beyond planar microchannels are mentioned: mesoreactors towards industrial level synthesis and micro-vessels for radiochemistry.

High-Efficiency Production of Radiopharmaceuticals via Droplet Radiochemistry: A Review of Recent Progress

“…Flow systems have highly uniform conditions within the reactor due to rapid mixing and high surface-to-volume ratio, and reactions have been observed to be very fast. [9][10][11] Using custom built and commercial flow systems, a wide range of different PET and SPECT tracers have been synthesized, including molecules labeled with fluorine-18, carbon-11, nitrogen-13, technetium-99, copper-64, zirconium-89, gallium-68, and lutetium-177. [12][13][14][15][16] In these systems, some steps of the tracer production process are performed using conventional macroscale setups (i.e., drying and activation of [ 18 F]fluoride upstream of the flow reaction, and purification of the crude tracer downstream of flow reaction), though some efforts have been made to implement them in a flow-like format.…”

On-demand generation and mixing of liquid-in-gas slugs with digitally programmable composition and size

“…The advantages of performing reactions in microreactors, such as improved speed, selectivity, and safety, are well-documented in the literature [1][2][3][4]. These advantages are believed to arise in large part from the precise control of temperature, facilitated by the high surface to volume ratio in microfluidic devices.…”