Microfabricated biochips are developed to continuously monitor cellular phenotype dynamics in a non-invasive manner. In the presented work we describe the novel combination of contact-less micro-dielectric sensors and microfluidics for quantitative cell analysis. The cell chip consists of a polymeric fluidic (PDMS) system bonded to a glass wafer containing the electrodes while temperature and fluid flow are controlled by external heating and pumping stations. Additionally, the cell chip contains an integrated reference arm providing a low-noise detection environment by eliminating background signals and interferences. The high-density interdigitated capacitors (µIDC) are designed to monitor living cells in a space of approximately 10 nL volume by controlling critical electrode characteristics, such as size, shape and passivation composition as well as thickness. The integrated µIDCs are isolated by a 300 nm multi-passivation layer of defined dielectric property and provide non-invasive, stable, robust and non-drifting measurement conditions. The performance of this detector is evaluated using various bacterial, yeast and mammalian cells.

Development of field portable apparatus and methods for cytokine assay of human saliva by fluorescent-reporting microarray plates is described. Multiplexed assay of 12 cytokines for minimally-processed saliva is read with a CCD-based imager under LED excitation. Immune responsive cytokines are measured at levels significant for indication of human disease state. The motivational context for the new apparatus development, the general optical design issues, saliva protocol, and image analysis are described.

One of the major problems in assembling efficient neuro-electronic hybrids systems is the low electrical coupling between the components. This is mainly due to the low resistance, extracellular cleft formed between the cell's plasma membrane and the substrate to which it adhere. This cleft shunts the current generated by the neuron, or the device and thus reduces the signal to noise ratio. To increase the clefts electrical resistance we fabricated gold micronails that protrude from the transistor gate surface. The micronails were functionalized by phagocytosis facilitating peptides. Cultured neurons readily engulf the functionalized micronails forming tight physical contact between the cells and the surface of the device

Microfluidic cell separation systems have emerged as attractive alternatives to traditional techniques in recent years. These systems offer the advantages of being able to handle small sample volumes and at the same time achieve highly selective separation. Conventional separation techniques, including both fluorescence-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS), typically require a pre-processing incubation step to attach ligated tags (such as fluorescent dyes or magnetic beads) to cell surfaces prior to separation. These techniques are also constrained by infrastructure and high cost. Microfluidic devices with surface-immobilized adhesion molecules eliminate the need for pre-processing incubation and are a low cost alternative.

We describe the selective adhesion of smooth muscle cells and endothelial cells in microfluidic devices coated with adhesion peptides. The device geometry is such that the shear stress varies linearly as a function of flow channel length, allowing simultaneous evaluation of the effects of surface chemistry and fluid shear on cell adhesion. The adhesion peptides, val-ala-pro-gly (VAPG) and arg-glu-asp-val (REDV), are known to bind selectively to smooth muscle cells and endothelial cells, respectively. These peptides were tethered to the device surface using silane chemistry and NHS-ester coupling. Cell adhesion was examined in a shear stress range of 1.3-4.0 dyn/cm2. Under these conditions, endothelial cells show significantly higher adhesion to REDV-coated devices compared to smooth muscle cells and fibroblasts. Correspondingly, smooth muscle cell adhesion in VAPG-coated devices is much greater than that of endothelial cells and fibroblasts. This selective binding behavior is also observed when mixed suspensions of the three cell types are flowed into both types of peptide-coated microfluidic devices. These results suggest that microfluidic devices coated with REDV and VAPG can be used as effective separation tools in various applications, such as tissue engineering. Specific examples of applications in cardiac and skin tissue engineering will be discussed.

The plug distortion for on-chip capillary zone electrophoresis systems with rectangular separation channels, manufactured in a hybrid layer system with different material properties of the vertical and the horizontal walls has been examined. Experimental data and simulation results indicate that plug widening caused by different values of the #950;-potential of the walls in contact with the fluid depends strongly on the aspect ratio of the channel cross section. If the height to width ratio is much greater or much smaller than 1, as is often the case for commonly used labchip architectures, plug widening may be negligible. The difference of the #950;-potentials between the vertical and the horizontal side walls has been determined from the shape of the plug edges. For an architecture using glass for the top and bottom walls, but SU-8 for the side walls, the difference of the #950; potentials was measured to be on the order of only 2.4 mV for a pH of 9.2, suggesting that such device architectures may be used for on-chip electrophoresis analysis without uniform coating of the channel inside for less demanding applications.

Application specific Lab-on-Microchips (ALMs) making use of the combination of complex microfluidic networks with microelectronic circuits and micro optical components allow the realization of miniaturized application specific biological and chemical processing and analysis devices. Fluorescence sensing is one of the most widely used detection technologies, e.g. for DNA fluorescence labelling in Micro Capillary Electrophoresis (µCE) due to its superior sensitivity and specificity. Unfortunately, commercially available fluorescence sensing systems are physically very large, non portable, expensive and constrain the analysis in portable diagnostic and medical care. Integrated semiconductor optoelectronic devices can provide a portable, parallel and inexpensive solution for on chip fluorescence sensing.

Most µCE applications working in the spectral range of visible light. For the integration of optical detection components a photon energy range of 1.6 eV - 3.1 eV is of interest. The a-Si:H technology accomplished due to the low dark current and high absorption coefficient against to crystalline silicon the requirements in that spectral range. In this paper we combine a:Si-H photo sensors with a fluidic micro system to detect the fluorescence of a rhodamine analyte mixture. The analyte mixture was excited by light with a wavelength in the range of λEx = 450 - 490 nm. The a-Si:H detector reveals a low dark current density on the order of 10-10 A/cm2 and a sufficient dynamic range of ∼100 dB under illumination of ∼1000 lx as a function of bias voltage. The measurement shows that the movement of the rhodamine plug in the microchannel causes a significant rise in the pin-diode photo current, which correlates to the evaluated signal of a microscope image detector. The photo current difference for excitation and additional fluorescence amounts to 2.4 µA.

This paper reports the fabrication of and characterization on EWOD(electrowetting-on-dielectric) devices on flexible substrates of interest to the flexible displays and devices. The EWOD devices were fabricated on PET (poly ethylene terephthalate) and PMMA (polymethylmethacrylate) substrates. Au and ITO(indium tin oxide) were used as electrode materials. The wet etching process was developed not to attack plastic flexible substrates. The photo resist was used as an insulator materials in EWOD devices due to the deformation of substrate when oxide layer was deposited on plastic substrate. As a hydrophobic layer, cytop was spin-coated on the photo resist. Wetting tests were done with DI water in air environment. In sessile droplet test, the contact angle of droplet changed from 116◦ to 80◦ under DC power. Threshold voltage was 20 Vdc. The droplet was oscillated under AC power because of the frequency. But the contact angle of droplet was began to change at 30Vac and decrease with the increase of AC power. In droplet transporting test, a droplet(0.2§¡) was started transporting at 20Vac and the transporting speed increased with the increase of AC power. But the droplet transporting was not occurred under DC power because of slower contact angle recovery rate under DC power.

The scope of the paper is to provide a theoretical and experimental treatment allowing to optimize critical design parameters for planar electroosmotic micropumps. The suggested design with a vertical arrangement of multiple narrow polymer pumping microchannels reduces the pump area to 1/10 compared to planar micropumps with widened shallow pumping channels. This design allows the fabrication of the channel system in only one process step, compatible with post-CMOS processing and suitable for monolithical integration on labchips. A simple analytical model has been developed to characterize the flow rate in a field free pressure-driven section of the channel. It is shown that the micropump with optimized dimensions of rib structures makes possible high pressure low voltage pumping. For high pressure capacity the distance between the ribs must be on the order of 0.5-1 µm with an aspect ratio of 10-20. The electroosmotic micropump with microchannels of SU-8 and polyacrylamide gel electrodes has been fabricated and tested. The pumping rate is bidirectionally linear and reached 10 nl/min at applied voltage of 40 V in 1 cm long pressure-driven channel, which corresponds to zero-flow pressure of 65 Pa.

A hydrogenated amorphous silicon photodetector on a glass substrate is used for the integrated, real-time detection of chemiluminescent reactions in solution. The light emission at 425 nm resulting from the horseradish peroxidase-catalyzed oxidation of luminol is detected by a p-i-n amorphous silicon photodiode operated at zero bias. The limit of detection of the present device is in the range of nanomole of horseradish peroxidase per liter.

We present a continuous flow scheme to produce hierarchically organized large emulsions and particles with very good control over size, shape and internal structure. By assembling together elementary co-axial flow modules and integrating their corresponding functions, modular set-ups can be designed “on demand” to engineer complex architectures in characteristic sizes ranging from 50 micrometers up to a few mm. The high potentiality of this approach stems from the continuous production of drops and the ability to manipulate and functionalize each one independently “on line”. Its great versatility is limited only by the number of combinations possible using the modular tool box and one's imagination. We illustrate this through the encapsulation of droplets or solid particles of various shapes, composition and size,in liquid or solidified drops as well as the formation of large organic or inorganic cylindrical particles.

We demonstrate functional microfabrications generated using photocurable functional polymers. We synthesized photocurable silicon elastomers, which can be useful for high fidelity, nano-scale soft lithography. ‘Elastic photopatterns’ generated by using the designed photocuarble silicon elastomers was presented. Molecularly imprinted polymers (MIP) are produced by “molecular imprinting technique”, which is a general protocol for the preparation of “synthetic receptor sites”. We then used the MIP's system for functional pattern fabrications to improve the sensitivity of molecular recognitions. Those functional microfabrications are beneficial to develop actual devices with high performances.

Dielectrophoresis switching with vertical microelectrodes in the side wall of microchannel have been designed, fabricated and tested. A set of interdigitated electrodes in the side wall of the microchannels is used for the generation of non-uniform electrical field to introduce DEP force to repel or attract beads/cells to the sidewalls. A countering DEP force is generated from another set of electrodes patterning on the opposing side walls. These DEP forces can be adjusted by the voltage and frequency applied. By manipulating the coupled DEP forces, the particles flowing through the microchannel can be positioned at different equilibrium points along the width direction and continue to flow into different outlets. The objects of interest can be switched to desired channel outlets in the flow with no need of any moving parts and the down-stream channel can be more than three outlets. Experimental results for switching cells to two outlets and polystyrene microbeads to five outlets have been achieved. The effect of the geometry and flow rate on the performance of the switching was studied and an analytical solution for the optimal design and operation of DEP electrode arrays has been derived from the proposed model.