High-resolution 3D-printed insulator-based dielectrophoresis devices for biomolecular manipulation

The advancement of microfluidics has enabled a wide range of biochemical and biological applications, such as high-throughput drug testing or point-of-care diagnostics, and has also enabled dielectrophoretic applications. Dielectrophoresis (DEP) is based on the movement of polarizable particles in a non-uniform electric field. Implementing insulator-based dielectrophoresis (iDEP) in microfluidic systems has provided a new dimension for the precise manipulation of biomolecules. However, iDEP has been hampered due to the often cumbersome and expensive microfabrication methods that are required, especially for sub-µm analytes, including biomolecules, since extremely large electric field gradients are needed to achieve successful iDEP manipulation. In recent years, 3D printing has drawn attention in microfluidics, alleviating several issues with cleanroom-based fabrication methods. Among the 3D printing repertoire, two-photon polymerization (2PP) is a novel 3D printing technique that offers unique capabilities with unprecedented resolution compared to standard stereolithography. Here, we report the first iDEP-based manipulation of biomolecules, namely, λ-DNA and Phycocyanin, within a completely 3D-printed microfluidic device realized with 2PP printing. iDEP microfluidic devices with different post geometries were 3D-printed and developed with a gap resolution down to 2 µm using the IP-S photoresist. Furthermore, sub-micrometer spatial resolution was achieved down to 800 nm using the IP-Dip photoresist. Additionally, a numerical model was developed to determine the electric field gradients, DEP trapping force, and infer the associated polarizability and DEP characteristics of the analytes. This 3D printing technology may offer impactful potential for rapid prototyping of novel iDEP microdevices and the opportunity to explore iDEP for various biomolecular applications in the future.