A new approach to design an efficient micropost array for enhanced direct-current insulator-based dielectrophoretic trapping.

Direct-current insulator-based dielectrophoresis (DC-iDEP) is a well-known technique that benefits from the electric field gradients generated by an array of insulating posts to separate or trap biological particles. The aim of this study is to provide a first geometrical relationship of the post array that independent of the particles and/or medium, maximizes the trapping. A novel figure of merit is proposed to maximize the particle trapping in the post array while minimizing the required voltage, with a similar footprint and channel thickness. Different post array models with the variation of transversal distance (10 to 60 μm), longitudinal distance (10 to 80 μm), and post radius (10 to 150 μm) were analyzed using COMSOL Multiphysics finite element software. The obtained results indicated that a post radius of 40 μm larger than the transversal distance between posts could enhance the trapping condition between 56 % (for a transversal distance of 10 μm) and 341 % (for a transversal distance of 60 μm). For the validation of the numerical results, several microchannels with embedded post arrays were manufactured in polydimethylsiloxane (PDMS) and the particle trapping patterns of 6-μm-diameter polystyrene particles were measured experimentally. The experiments confirm the same trends as pointed out by the numerical analysis. The results show that this new figure of merit and geometrical relationship can be used to reduce the required electric field to achieve effective particle trapping and, therefore, avoid the negative effects of Joule heating in cells or viable particles. The main advantage of these results is that they depend only on the geometry of the micropost array and are valid for trapping different particles suspended in different media. Graphical abstract Analysis to maximize the particle trapping in the post array while minimizing the required voltage. I. Microfluidic channel design and experimental setup II. Numerical and experimental results. III. Maximum trapping value.