Light technology is based on generating, detecting and controlling the wavelength, polarization and direction of light. Emerging applications range from electronics and telecommunication to health, defence and security. In particular, data transmission and communication technologies are currently asking for increasingly complex and fast devices, and therefore there is a growing interest in materials that can be used to transmit light and also to control the distribution of light in space and time. Here, we design chiral nematic microspheres whose shape enables them to reflect light of different wavelengths and handedness in all directions. Assembled in organized hexagonal superstructures, these microspheres of well-defined sizes communicate optically with high selectivity for the colour and chirality of light. Importantly, when the microspheres are doped with photo-responsive molecular switches, their chiroptical communication can be tuned, both gradually in wavelength and reversibly in polarization. Since the kinetics of the “on” and “off” switching can be adjusted by molecular engineering of the dopants and because the photonic cross-communication is selective with respect to the chirality of the incoming light, these photo-responsive microspheres show potential for chiroptical all-optical distributors and switches, in which wavelength, chirality and direction of the reflected light can be controlled independently and reversibly.

Electrochemical anodization has been applied to grow porous shell layers of 300 nm (30 nm pores) in 5 μm diameter pillar array columns (PACs) with a spacing of 2.5 μm. Using turn structures preceded and followed by the flow distributor structures recently introduced by our group and filled with radially elongated pillars, columns with quasi unlimited channel lengths could be conceived. The uniformity of the porous PAC was assessed by determining local plate heights along the channel, which appeared to be constant. Minimal (absolute) plate heights (H) between 4 and 6 μm were obtained at optimal flow rates when imposing increasing retention factors. Upon measuring the surface area involved in chromatographic retention as an indicator of the available surface area, an increase in the surface area by a factor of about 30 compared to that of non-anodized pillars was found. On reconfiguring a commercial HPLC instrument to enable on-chip injections, 90% of the performance (expressed in theoretical plates) could be maintained for a 1 m column, while for a 25 cm column severe losses were still observed. As the corresponding pressure drop for optimal operation of retained components is on the order of 10 bar per m only, portable and cheaper HPLC devices with high efficiencies become realistically conceivable.

An experimental study comparing the performance of different designs for microfabricated column structures for microchip capillary electrochromatography is presented. The work is a follow-up to our previously published modeling and simulation study on the same topic. Experiments were performed using fused silica microchips with and without octadecyltrimethoxysilane coating for nonretained and retained modes of operation, respectively. Showing the same trends as the modeling results, the foil shape produces a significant decrease in plate height with an increase of around 15% in mobile phase velocity in nonretained measurements of Coumarin 480 (C480). Measured plate heights at 1 kV/cm applied electric field were 0.77, 1.33, and 1.42 μm for foil, diamond, and hexagon, respectively. Chromatographic runs of C480 yielded minimal plate height values of 1.85 and 3.28 μm for foil and diamond, respectively. The optimization of the shape and placement of the structures appeared to have a considerable impact on the achievable performance.

We present a lab-on-a-disk technology for fast identification and quantification of parasite eggs in stool. We introduce a separation and packing method of eggs contained in 1 g of stool, allowing for removal of commonly present solid particles, fat droplets and air bubbles. The separation is based on a combined gravitational and centrifugal flotation, with the eggs guided to a packed monolayer, enabling quantitation and identification of subtypes of the eggs present in a single field of view (FOV). The prototype was tested with stool samples from pigs and humans infected with intestinal parasites (soil-transmitted helminths eggs). The quality of the images created by this platform was appropriate for identification and quantification of egg types present in the sample.

We present a novel electrode configuration consisting of coplanar side electrode pairs integrated at the half height of the microchannels for the creation of a homogeneous electric field distribution as well as for synchronous optical and electrical measurements. For the integration of such electrodes in fused silica microsystems, a dedicated microfabrication method was utilized, whereby an intermediate bonding layer was applied to lower the temperature for fusion bonding to avoid thereby metal degradation and subsequently to preserve the electrode structures. Finally, we demonstrate the applicability of our devices with integrated electrodes for single cell electrical lysis and simultaneous fluorescence and impedance measurements for both cell counting and characterization.

Studying binding interactions involving living cells requires a platform that carefully mimics the physiological parameters that govern these phenomena. Very often the amount of ligands that receptors can bind affect overall binding strength as is the case in cell adhesion. In addition, the physical environment can strongly influence these processes. This is exemplified by the effect of shear stress in catch‐bond‐mediated binding of bacteria. Traditional analysis techniques do not allow to probe these factors simultaneously. To this end, continuous ligand gradients in locked‐in supported lipid bilayers (SLBs) are prepared in a microfluidic device to control fluid flow. This platform allows for one‐pot characterization of cell surface binding events and 1) the effect of ligand density and 2) shear stress, simultaneously. The model interaction between the FimH receptor found on Escherichia coli and mannose found on the mammalian cell membrane is used to evaluate the platform. Using a single chip, specific E. coli ORN 178 adhesion (K d of 0.9 × 10−21 m), detachment and displacement are shown to depend on the mannose‐density and shear stress. For the first time, these effects are studied in a single chip device with high quality. This chip provides entry to further our understanding of other cell–cell interactions.

A novel design approach for optimizing the shape of microfabricated pillar columns for LC is presented. 2-D flow simulations are performed with a focus on electrokinetically driven flow, in order to evaluate the performance of the new method. The proposed foil shape is compared with geometrical shapes known from the literature, for various arrangements. It yields a much more uniform velocity field distribution and a decrease in plate height values up to 25%. In addition to shape optimization, a new method for spatial arrangement of structures is presented. With the aim of conserving the hydrodynamic balance, the axial spacing of the pillars is adjusted according to the proposed equivalent width approach. When compared with a fixed interpillar spacing in all directions, it increases the flow uniformity and results in an 18% lower plate height. A new direct simulation approach is implemented to model both flow field and retention for solid microfabricated pillar structures in the 2-D domain. This model, which defines retention as inward/outward fluxes through the wall surfaces as first order reactions, enables monitoring of the time-dependent process and an evaluation of the parameters affecting performance. The meaning of the obtained results in a practical setting, with limitations in photolithography and microfabrication, will be highlighted.

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