Injection Molding of Thermoplastics for Low-Cost Nanofluidic Devices

Abstract

Thermoplastic micro- and nanofluidics are increasing in popularity due to their favorable chemical and physical properties as an alternative to poly(dimethyl siloxane) (PDMS)-based devices, which are more widely used in academia. Additionally, their fabrication is compatible with industrial processes, such as hot embossing and injection molding. Nevertheless, producing devices with sub-micrometer channel heights and low roughness while retaining high-throughput molding remains challenging. This article details the combination of grayscale e-beam lithography (g-EBL) and injection molding as a fabrication route for capillary 3D thermoplastic nanofluidic devices with unprecedented accuracy in the sub-micrometer range. We employed g-EBL to pattern the device profile in a poly(methyl methacrylate) (PMMA)-based resist, which served as a substrate for the subsequent fabrication of a negative nickel mold by using electroforming. These molds are used to fabricate devices in PMMA and cyclic olefin polymers (COP) using injection molding. We show that the 3D height profile of the nanofluidic devices is maintained throughout the entire replication cycle within very tight tolerances, retaining its nanoscale topography on a millimeter-length scale. Moreover, somewhat surprisingly, the roughness in the inflow section of the devices was significantly reduced, which we attribute to the nickel mold fabrication. Last, we show that the capillary-driven devices can be used to size-dependently trap nanoparticles of various sizes in a reliable and facile manner while only requiring a 4 μL sample volume. The presented device and fabrication procedure paves the way for applications in various scientific fields, ranging from immunology to neurology and material science, in a cost-effective manner.

Impact of Injection Molding Parameters on Material Acoustic Parameters

“…It is common to conduct initial studies on the material, the conditions, and the process parameters to achieve such consistency using various methods [5]. In recent years, IM has found significant applications in the biomedical industry, for example, in microfluidics and lab-on-a-chip devices [6]. Acoustic lab-on-a-chip systems, which utilize ultrasonic waves to manipulate biological samples, have increased in prominence due to their potential for non-invasive and accurate sample processing.…”

Electrohydrodynamic Nanopatterning: A Novel Solvent-Assisted Technique for Unconventional Substrates

“…An epoch of revolutionized micro- and nanoelectronics development has unfolded, largely attributable to the extensive contributions from lithographic techniques . Proven instrumental in the growth of a diverse range of industries, including integrated circuits, metasurfaces, , semiconductor devices, − micro/nanofluidic devices, − sensors, , and wettability-controlled surfaces, , these techniques have paved the way for substantial progress in the field of micro/nanofabrication. ,, Underscored by an increasing demand for emergent functionalities on intricately structured films or high-performance devices, alternative lithographic techniques are being vigorously pursued to enable low-cost micro/nanopattern manufacturing. , …”