Study on mixing characteristics in shaken microwell systems

Abstract

Shaken microwell plates are widely used for early bioprocess development as they allow a large number of experiments to be performed in parallel by using small amount of materials. Despite their widespread use, microwell plates have not been characterised from an engineering viewpoint. In this study, mixing time measurements were carried out in two wells of square and cylindrical cross sections for small orbital diameter shaker, do = 3 mm, commonly used in commercial microwell platforms (i.e. ThermoMixer) and compared against measurements obtained in lab scale reactors for larger orbital diameters. The Dual Indicator System for Mixing Time (DISMT) method was employed for all the operating conditions investigated, and a range of rotational speeds was identified where mixing is less effective due to reduced free surface oscillation. An effective scaling parameter between microwell platforms and lab scale reactors was identified based on the natural frequency of the system, which depends only on fill volume, size and cross section of the reactor.