Digital fabrication of support structures for improved mechanical stability of fragile microsieves

We introduce a method to improve the mechanical stability of thin sieves by applying a support matrix through inkjet printing. Different suitable materials are printed in defined structures, such as honeycombs, either directly on the sieve or on a subcarrier. The digital technology allows the variation of the three-dimensional geometry of the printed pattern, whereby an optimum has to be found between the coverage of the pores, the permeability of the microsieve and its mechanical stability. The benefit of this method is the opportunity to produce and apply the microsieves in large-area-applications

Single-colloidal particle impedance spectroscopy: complete equivalent circuit analysis of polyelectrolyte microcapsules

We present a high-speed microfluidic technique for characterizing the dielectric properties of individual polyelectrolyte microcapsules with different shell thicknesses using single-particle electrical impedance spectroscopy. Complete equivalent circuit analysis is developed to describe the electrical behavior of solid homogeneous microparticles and shelled microcapsules in suspension. The complete circuit model, which includes the resistance of the shell layer and the capacitance of the inner core, has been used to determine the permittivity and conductivity in the shell of single capsules. The PSpice circuit simulations, based on the developed complete circuit models, are used to analyze the experimental data. The relative permittivity of the polyelectrolyte capsule shell is determined to be 50, and the conductivities of the shells of six- and nine-layer microcapsules are estimated to be 28 ±6 and 3.3 ±1.7 mS m-1, respectively