Bio‐microfluidics: Biomaterials and Biomimetic Designs

Abstract

Bio-microfluidics applies biomaterials and biologically inspired structural designs (biomimetics) to microfluidic devices. Microfluidics, the techniques for constraining fluids on the micrometer and sub-micrometer scale, offer applications ranging from lab-on-a-chip to optofluidics. Despite this wealth of applications, the design of typical microfluidic devices imparts relatively simple, laminar behavior on fluids and is realized using materials and techniques from silicon planar fabrication. On the other hand, highly complex microfluidic behavior is commonplace in nature, where fluids with nonlinear rheology flow through chaotic vasculature composed from a range of biopolymers. In this Review, the current state of bio-microfluidic materials, designs and applications are examined. Biopolymers enable bio-microfluidic devices with versatile functionalization chemistries, flexibility in fabrication, and biocompatibility in vitro and in vivo. Polymeric materials such as alginate, collagen, chitosan, and silk are being explored as bulk and film materials for bio-microfluidics. Hydrogels offer options for mechanically functional devices for microfluidic systems such as self-regulating valves, microlens arrays and drug release systems, vital for integrated bio-microfluidic devices. These devices including growth factor gradients to study cell responses, blood analysis, biomimetic capillary designs, and blood vessel tissue culture systems, as some recent examples of inroads in the field that should lead the way in a new generation of microfluidic devices for bio-related needs and applications. Perhaps one of the most intriguing directions for the future will be fully implantable microfluidic devices that will also integrate with existing vasculature and slowly degrade to fully recapitulate native tissue structure and function, yet serve critical interim functions, such as tissue maintenance, drug release, mechanical support, and cell delivery.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

“…Unfortunately, the current limitations of most electroactive polymer materials prevent their use in many practical applications, but this situation is bound to change given the broad interest in improving them. With the convenience and near ubiquity of physically soft materials in microfluidics, particularly as of late with biomimicry and tissue engineering (Domachuk et al, 2010) for implants, these materials may prove superior in many applications for acoustically actuating fluids in microfluidics by making acoustic excitation within the castable components such as PDMS possible.…”

“…By itself, microfluidics (Stone et al, 2004) is a flourishing research area that has swiftly emerged from microelectronics over the past 15 years. Delivering technology useful for applications in biochemistry and medicine requires an enormous effort to merge these fields with engineering and physics expertise in the fundamentals and fabrication methods of microfluidics (Beebe et al, 2002;Weibel et al, 2007;Domachuk et al, 2010), an effort that remains essentially incomplete. Furthermore, there are a number of significant physical forces present at these scales relevant to microfluidics, from interatomic to microscale, that are comparatively insignificant at larger scales associated with traditional fluid mechanics (Wautelet, 2001).…”

Biomimetic micro/nanostructured functional surfaces for microfluidic and tissue engineering applications

“…19,20 Nature teaches us that special wetting characteristics can be achieved through the synergy of micro-and nanoroughness and surface chemistry. In the past few years, there have been remarkable advances in the understanding of wetting properties of rough surfaces.…”

With great structure comes great functionality: Understanding and emulating spider silk

“…For applications such as coatings, optics, non load-bearing scaffolds, wound dressing, and drug delivery systems, current spinning and deposition technology produces useful materials. 96,97 The quest to recreate the spinning conditions that would allow us to match, or even exceed, the properties of native spider silks remains in its infancy and is largely in the domain of intellectual property rather than the scientific literature. 98,99 A promising approach to fiber synthesis is emerging from the field of microfluidics, 100 which provides a tunable fabrication process that allows for customizable fiber formation.…”