Next-Generation Microfluidics for Biomedical Research and Healthcare Applications

Microfluidic systems offer versatile biomedical tools and methods to enhance human convenience and health. Advances in these systems enables next-generation microfluidics that integrates automation, manipulation, and smart readout systems, as well as design and three-dimensional (3D) printing for precise production of microchannels and other microstructures rapidly and with great flexibility. These 3D-printed microfluidic platforms not only control the complex fluid behavior for various biomedical applications, but also serve as microconduits for building 3D tissue constructs-an integral component of advanced drug development, toxicity assessment, and accurate disease modeling. Furthermore, the integration of other emerging technologies, such as advanced microscopy and robotics, enables the spatiotemporal manipulation and high-throughput screening of cell physiology within precisely controlled microenvironments. Notably, the portability and high precision automation capabilities in these integrated systems facilitate rapid experimentation and data acquisition to help deepen our understanding of complex biological systems and their behaviors. While certain challenges, including material compatibility, scaling, and standardization still exist, the integration with artificial intelligence, the Internet of Things, smart materials, and miniaturization holds tremendous promise in reshaping traditional microfluidic approaches. This transformative potential, when integrated with advanced technologies, has the potential to revolutionize biomedical research and healthcare applications, ultimately benefiting human health. This review highlights the advances in the field and emphasizes the critical role of the next generation microfluidic systems in advancing biomedical research, point-of-care diagnostics, and healthcare systems.

Noncontact Multiphysics Probe for Spatiotemporal Resolved Single-Cell Manipulation and Analyses

Heterogeneity and spatial arrangement of individual cells within tissues are critical to the identity of the host multicellular organism. While current single-cell techniques are capable of resolving heterogeneity, they mostly rely on extracting target cells from their physiological environment and hence lose the spatiotemporal resolution required for understanding cellular networks. Here, a multifunctional noncontact scanning probe that can precisely perform multiple manipulation procedures on living single-cells, while within their physiological tissue environment, is demonstrated. The noncontact multiphysics probe (NMP) consists of fluidic apertures and "hump" shaped electrodes that simultaneously confine reagents and electric signals with a single-cell resolution. The NMP's unique electropermealization-based approach in transferring macromolecules through the cell membrane is presented. The technology's adjustable spatial ability is demonstrated by transfecting adjacent single-cells with different DNA plasmid vectors. The NMP technology also opens the door for controllable cytoplasm extraction from living single-cells. This powerful application is demonstrated by executing multiple time point biopsies on adherent cells without affecting the integrity of the extracted macromolecules or the viability of cells. Furthermore, the NMP's function as an electro-thermal based microfluidic whole-cell tweezer is reported. This work offers a multifunctional tool with unprecedented probing features for spatiotemporal single-cell analysis within tissue samples.

3D Printed Microfluidic Probes

In this work, we fabricate microfluidic probes (MFPs) in a single step by stereolithographic 3D printing and benchmark their performance with standard MFPs fabricated via glass or silicon micromachining. Two research teams join forces to introduce two independent designs and fabrication protocols, using different equipment. Both strategies adopted are inexpensive and simple (they only require a stereolithography printer) and are highly customizable. Flow characterization is performed by reproducing previously published microfluidic dipolar and microfluidic quadrupolar reagent delivery profiles which are compared to the expected results from numerical simulations and scaling laws. Results show that, for most MFP applications, printer resolution artifacts have negligible impact on probe operation, reagent pattern formation, and cell staining results. Thus, any research group with a moderate resolution (≤100 µm) stereolithography printer will be able to fabricate the MFPs and use them for processing cells, or generating microfluidic concentration gradients. MFP fabrication involved glass and/or silicon micromachining, or polymer micromolding, in every previously published article on the topic. We therefore believe that 3D printed MFPs is poised to democratize this technology. We contribute to initiate this trend by making our CAD files available for the readers to test our "print & probe" approach using their own stereolithographic 3D printers.

Stagnation point flows in analytical chemistry and life sciences

Isolated microfluidic stagnation points – formed within microfluidic interfaces – have come a long way as a tool for characterizing materials, manipulating micro particles, and generating confined flows and localized chemistries.

Merging orthogonal microfluidic flows to generate multi-profile concentration gradients

This work describes a novel microfluidic device capable of generating multi-profile gradients that include sigmoidal, parabolic, and exponential concentration variations across its main channel.