Micro-electro-opto-fluidic systems for biomedical drug screening and electromagnetic filtering and cloaking applications
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Microfluidic is a multidisciplinary field that deals with the flow of liquid inside micro-meter size channels. In order to be considered as microfluidics, at least one dimension of the channel should be in the range of one micrometer or sub-millimeter. Microfluidic technology includes designing, manufacturing, formulating devices and processing the liquid. As numerous bio-science and engineering techniques have utilized microfluidics and highly integrated with this remarkable technology, the microfluidic platform technology has extended to several sub-techs: micro-scale analysis, soft-lithography fabrication, polymer science and processing, on-chip sensing and micro-scale fluid manipulation. Those sub-techs have been developed rapidly along with the booming microfluidics.
The advance of those techniques has promoted microfluidic system diverse and widespread applications. Some examples that employ this technology include on-chip drug screening, micro-scale analysis, flexible electronics, biochemical assays. Many engineering field, such as optics, electronics, chemicals and electromagnetics, have been integrated with the microfluidic system to form a completed system for sensing, analyzing or realizing some specific applications.
Through the fusion of those technologies with microfluidics, many emerging technologies are well initiated, such as optofluidics and electrofluidics. Despite of rapid advancement of each parent technology field, those intersected technologies are still in their infancy and many technological elements and even some fundamental concepts are just now being developed. Thus, it provides great opportunity to explore more about those emerging technologies. Some particular areas that mainly interest researchers including cost deduction, effective fabrication, highly integration, portability and applicability. Due to the wide and diversity nature of the microfluidic technology and numerous combinations from the integration with other fields, it is very difficult to choose a single aspect or particular subject to research. Hence, we would like to focus on the application orientated microfluidic techniques that integrated with other engineering areas, in particular optics and electronics. Correspondingly, I will present four microfluidic platforms that integrated with optics, electronics for different application purpose.
First of all, fiber-optics was integrated into a microfluidic device to detect muscular force generation of microscopic nematodes. The integrated opto-fluidic device is capable of measuring the muscular force of nematode worms normal to the translational movement direction with high sensitivity, high data reliability, and simple device structure. The ability to quantify the muscular forces of small nematode worms will provide a new approach for screening mutants at single animal resolution.
Secondly, electronic grids were integrated into a microfluidic chip to realize on-chip tracking of nematode locomotion. The micro-electro-fluidic approach is capable of real-time lens-less and image-sensor-less monitoring of the locomotion of microscopic nematodes. The technology showed promise for overcoming the constraint of the limited field of view of conventional optical microscopy, with relatively low cost, good spatial resolution, and high portability.
Thirdly, electromagnetic spit ring resonator (SRR) structure was adopted as microfluidic channel filled with liquid metal to fabricate a tunable microfluidic microwave electronics called meta-atom. The presented meta-atom is capable of tuning its electromagnetic (EM) response characteristics over a broad frequency range via simple mechanical stretching. The meta-atom in this study presents a simple but effective building block for realizing mechanically tunable metamaterials.
Finally, based on the meta-atom we previously developed, an array of electromagnetic SRR shaped microfluidic channels filled with liquid metal to form a flexible metamaterial-based microwave electronic “skin” or meta-skin. When stretched, the meta-skin performs as a tunable frequency selective surface with a wide resonance frequency tuning range. When wrapped around a curved dielectric material, the meta-skin functions as a flexible “cloaking” surface to significantly suppress scattering from the surface of the dielectric material along different directions.
The microfluidic platform will find great applications when it integrates with other technologies. The development of such integration will greatly intersect different research areas and benefit all of the intersected technologies and fields, thus broadening the future applications.