Passive fluid delivery

While we have demonstrated the successful application of our integrated organic photodiode-based test platform to antioxidant capacity determination, we regard this as a first step towards a universal platform for chemiluminescence-based testing at the point-of-care. To this end we have investigated the use of passive fluid delivery schemes (to circumvent the use of valves and external pumps) and the implementation of low-cost electronic read-out circuits (for both size and cost reduction). 

Droplet delivery from an airblast nebulizer is governed by the surface tension, density and viscosity of the fluid, and the applied pressure, which can be passive or forced. Droplet breakup is illustrated in Fig. 6. Droplets form during this breakup at a critical Weber number (We) ... 

In addition to passive diffusion, channels, and carrier proteins, a fourth mechanism of breaching biological membranes is provided by vesicle-mediated transport, which can also be used for drug delivery. Endocytosis refers to the uptake of cell surface constituents by the formation of vesicles from the plasma membrane. This process can be subclassified into phagocytosis, the engulfment of particles, and pinocytosis, the engulfment of fluid. 

Up to now, the development of microneedles has focused on microfabrication techniques for Si and other biocompatible materials. Currently, there are several commercially available microneedle products, such as MTS (Microstructured Transdermal System) by 3 M, Macroflux by ALZA, and Micro-Trans by Bio Valve Technologies, and most of them are designed to increase skin permeability and adopt passive delivery methods (i.e., capillary force). As the feasibility of microneedles is well established, the next step is to understand the characteristics of fluid transport by microneedles,... 

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