## 1 Introduction  
Numerous research areas, such as regenerative medicine, tissue engineering, biotechnology, drug discovery, and cancer research, treatment, and diagnostics, rely on fundamental techniques of cell separation, sorting, and analysis. One method that has arisen interest in the last few decades within the variety of sorting techniques is the microfluidic-based cell separation method [1]. Microfluidic devices allow the \"handling of fluids in technical apparatus having internal dimensions in the range of micrometres up to a few millimetres\". Some of the main advantages of microfluidic devices are the existence of a laminar flow within the system, the possibility of direct interactions with cells, faster and parallel sample analysis, increased surface-to-volume ratio, as well as the possibility of device automation [2]. Among the most known microfluidic devices is the H-type filter, which takes advantage of the diffusive mixing between the adjacent laminar streams to facilitate the passive separation of particles. By means of controlling parameters such as the channel geometry and flow rate, the diffusion time of the particles within the flow can be limited, therefore achieving cell isolation, manipulation, and separation [3]. These properties of the microfluidic devices, together with their ability to provide unique control over the flow conditions, high throughput, and the capacity to emulate in vivo-like biological environments, make them promising platforms for bacterial biofilm observation and research [4]. A novel method in the fabrication of microfluidic systems is additive manufacturing (AM). AM for microfluidic devices is attracting widespread interest [5] due to its revolutionary approach of creating parts or prototypes layer-by-layer directly from a computer-aided design (CAD). One AM method that stands out is fused deposition modelling (FDM), which allows the use of numerous biocompatible thermoplastic polymers for the fabrication of different printed parts. Some of the most recent works employ the 3D printing technique for the fabrication of flexible thermoplastic polyurethane microfluidic devices [6], high-pressure, heat-resistant, transparent PLA devices [7], and even 3D printed microfluidic devices with integrated materials such as wires, glass and electrodes [5; 8]. Moreover, 3D printing allows for the production of customizable devices, with structural components such as porosity, pore-to-pore distance, geometry, and surface roughness specially tailored for specific applications. From generating forebrain-specific organoids from human induced pluripotent stem cells (iPSCs) [9] through miniaturized, modular spinning bioreactors, to high-throughput fabrication of hydrogel scaffold droplets for cell encapsulation [10], and directly immobilizing and maintaining the viability and functionality of 3D multicellular spheroids [11], 3D printed microfluidic devices have proven to be an unparalleled and vital platform for studying single cells, large cell populations, cell interactions, and organoids [12]. Therefore, for this research, the FDM 3D printing method was chosen. Throughout the years, various particle manipulation techniques within microfluidic devices were developed, including methods based on properties such as:  
* optical properties [13; 14] for cell sorting, trapping, single-cell analysis, molecule injection, and electroporation;
* magnetic properties [15] for cell separation, capturing, trapping, isolation, and analysis;
* electric properties [16; 17; 18] for cell separation, focusing, isolation, and cell fusion;
* mechanical properties [19], for cell separation, focusing, isolation, analysis, and diagnosis;
* others [20]. Within these techniques, the most suitable for bioparticle manipulation are the methods based on electrical fields as a result of their strong controllability, high efficiency, and easy operation [21].