Innovations in Microfluidics 2024: Rapid Prototyping, 3D-Printing Agenda

3D-Printed Epidermal Microfluidic Systems
Tyler Ray, Professor, University of Hawaii at Manoa, United States of America

An emerging class of wearable devices integrates microfluidic lab-on-chip designs with low-modulus materials, colorimetric assays, and electrochemical sensors to support the real-time, non-invasive analysis of sweat. Such skin-interfaced microfluidic systems offer powerful capabilities for personalized assessment of health, nutrition, and wellness through the non-invasive, real-time analysis of sweat. Initially simple systems of microfluidic channels, current devices comprise sophisticated networks channels, valves, and reservoirs with some embodiments employing multilayer design strategies. While these platforms exhibit powerful analytical capabilities, device fabrication requires time, labor, and resource-intensive cleanroom processing, which restricts the device design space (2D) and elongates the development time. Additive manufacturing processes, particularly stereolithography (SLA)-based printing, offer powerful pathways for overcoming these limitations by providing significant reductions in prototype development cost and cycle time while substantially expanding device capabilities with fully 3D device designs. Here, we present a simplified 3D-printing prototyping process to fabricate flexible, stretchable, epidermal microfluidic devices (‘3D-epifluidics’). Reducing fabrication time to [O]min, this approach enables the integration of spatially-engineered features including 3D-structured passive capillary valves, monolithic channels, and reservoirs with spatially-graded geometries. With geometric features comparable to established epifluidic devices (channels >50 µm), benchtop and on-body testing validate the performance of 3D-epifluidic devices.

3D-Printed Microfluidic Circuitry via Alternative Additive Manufacturing Strategies
Ryan Sochol, Associate Professor, University of Maryland, College Park, United States of America

Over the past decade, researchers have demonstrated that additive manufacturing—or “three-dimensional (3D) printing”—approaches provide powerful means for achieving integrated microfluidic circuits and systems.  Although the majority of developments in the area of 3D-printed microfluidic circuitry have relied on mesoscale “vat photopolymerization” techniques, such as “stereolithography”, there are a wide range of additive manufacturing approaches that offer utility for microfluidic circuit design, fabrication, and integration.  In this talk, Prof. Ryan D. Sochol will discuss how his Bioinspired Advanced Manufacturing (BAM) Laboratory is leveraging the capabilities of alternative additive manufacturing technologies—namely “PolyJet 3D Printing” and “Two-Photon Direct Laser Writing”—to realize 3D-printed microfluidic circuits for soft robotic applications… including a soft robotic “hand” that plays Nintendo.

Expanding the Droplet-Microfluidics Toolkit with Electrokinetics
Robbyn Anand, Associate Professor, Iowa State University, United States of America

Droplet-based techniques have had a profound impact in biotechnology, owing to an ability to perform rapid and massively parallel reactions in minute fluid volumes. However, once droplets are formed, their composition can be altered through limited functions including the addition of reagents through droplet merging, which increases droplet volume, and through in-droplet mixing. Further, while droplet contents can be measured through, there remains a need for more versatile methods to probe droplets without significantly altering their contents. In this presentation, we describe a suite of in-droplet electrokinetic methods including de-mixing, mobility-based separations, desalting, and “salting”. Finally, we will share initial results for the measurement of the ionic content of droplets.

A High Resolution, SLA PDMS Resin and its Application in Microfluidic Organ Models
Joseph Potkay, Research Assistant Professor, University of Michigan, Clinical Research Engineer, VA Ann Arbor Healthcare System, United States of America

This presentation will cover our progress toward developing and characterizing a high resolution and biocompatible polydimethylsiloxane SLA 3D printing resin and its use to create various microfluidic structures including microfluidic artificial lungs.