FABRICATION OF PICOLITER TO MICROLITER STRUCTURES IN ONE CHIP USING HYBRID COC FILM TECHNOLOGY

We introduce a rapid, cost-effective method for integrating pico-to microfluidic structures on a single chip, bridging the gap between fast but non-scalable polydimethylsiloxane (PDMS) fabrication and scalable yet time-intensive thermoplastic injection molding.This approach facilitates chip fabrication in cyclic olefin copolymer (COC), a product-grade thermoplastic polymer, circumventing non-scalable materials.Our method combines a microliter-domain structured film (e.g.channels and chambers) with a picoliter-domain structured film (e.g.cavities and pillars) via thermal sealing.We demonstrate the fabrication of three distinct picoliter-sized patterns in COC microfluidic chips, displaying the feasibility and versatility of the process.With its rapid turnaround time and low tooling costs, our method enables swift design iterations for applications requiring structures ranging from pico-to microliters. INTRODUCTION:Numerous lab-on-a-chip applications require integrating pico-(e.g.reaction cavities) to microliter (e.g.inlet chambers) structures, such as for digital assays [1].Hybrid fabrication processes merge lithography (nanometer-resolution) for picoliter-sized patterns with methods like micro-milling (micrometerresolution) for microliter-sized structures.However, these methods often rely on non-scalable PDMS techniques [2], or silicon chips [3], or time-consuming injection molding tools [4].We propose a novel, low-cost, and swift method for integrating pico-to microliter structures into a COC chip by combining nanoimprinting, microthermoforming, and thermal sealing, resulting in a three-step process (Fig. 1).