A Continuous Flow Microreactor with a Spiral Channel is an advanced microfluidic reactor that uses the geometry of a spiral to enhance mixing and heat transfer through centrifugal forces.

The most significant advantage of a spiral channel over a straight or serpentine channel is the generation of Dean Vortices. (1) Secondary Flow: As fluid moves through the curve, centrifugal forces push the faster-moving center fluid toward the outer wall. To compensate, fluid near the walls recirculates toward the inner curve. (2) Chaotic Advection: These two counter-rotating vortices (Dean Flow) effectively "fold" and "stretch" the fluid streams. This achieves high-efficiency mixing even at low Reynolds numbers where flow would otherwise be purely laminar and slow-diffusing. (3) Mixing Index: Spiral mixers can achieve >90% mixing efficiency in a fraction of the length required by a straight channel.  

References:

T. Razzaq, et al., Continuous-Flow Microreactor Chemistry under High-Temperature/Pressure Conditions, European Journal of Organic Chemistry, 2009, 9, 1321-1325.

M. Atobe, et al., Applications of Flow Microreactors in Electrosynthetic Processes, Chem. Rev. 2018, 118, 9, 4541–4572.

J. I. Yoshida, et al., Flash chemistry: flow microreactor synthesis based on high-resolution reaction time control, The Chemical Record, 2010, 10, 332-341