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Micro molding for double-sided micro structuring of SU-8 resist

Advances in micro and nano fabrication technologies for MEMS require high-level measurement techniques with regard to sampling and sensitivity. For this purpose at the Institute of Microtechnology (IMT) highly sensitive piezoresistive 3D force sensors based on SU-8 polymer have been developed. In this paper we present an improved micro fabrication process for a double-sided micro structured design. The sensors are produced by multilayer processing techniques such as UV lithography and coating methods. The double-sided micro structured design demands a photoresist application method which simultaneously features a top side structuring and a casting from a mold. We use a new micro molding process to meet the demands. The micro fabrication technology is described, focusing on the development of the molding structure for shaping of the bottom side and a capable release process for the detachment of the molded structures. The fabrication process of the SU-8 mold layer is optimized to fabricate molding structures with heights from a few μm up to 350 μm. Therefore different SU-8 formulations, namely with classification numbers 5, 25, 50, and 100, have been used. The fundamental limitations for the mold design result from the lithography process, which defines the smallest lateral resolution, and from the characteristics of a molding process, e.g. the impossibility to realize an undercut. To allow for reliable release, the molding structures have to be coated with a sacrificial layer. Silicon nitride is deposited onto the substrate with accompanying monitoring of the deposition temperature during the PECVD process.     

An Asymptotic Preserving Method for Linear Systems of Balance Laws Based on Galerkin’s Method

We apply the concept of asymptotic preserving schemes (SIAM J Sci Comput 21:441–454, 1999) to the linearized \(p\) -system and discretize the resulting elliptic equation using standard continuous Finite Elements instead of Finite Differences. The fully discrete method is analyzed with respect to consistency, and we compare it numerically with more traditional methods such as Implicit Euler’s method.     

Study of the Catalytic Ozonation of Humic Substances in Water and Their Ozonation Byproducts

It is shown that using transition metals, especially Mn(II) and Ag(I), during ozonation of humic substances in water allows important reductions in the content of organic matter. Characterization of the organic compounds resulting from ozonation was made by concentrating the sample through liquid-liquid extraction or derivation with PFBOA.HCl, along with the GC/MS and GC/ECD techniques. In total, 110 different organic compounds were identified using GC/MS; mainly carboxylic acids, aromatics, hydrocarbons, aldehydes, ketones, and furan-carboxylic acids. The percentages of elimination or formation levels reached during ozonation are discussed.     

Tailoring of Surfaces with Ultrathin Layers for Controlled Binding of Biopolymers and Adhesion and Guidance of Cells

Various strategies are described for the bio-functionalization of solid substrates by design of interfacial architectures. The first approach is based on the self-assembly process of long-chain thiol molecules from solution to a (noble) metal surface. If some of these building blocks carry a binding site (ligand) for proteins (receptors, antibodies, etc.) the metal surface can be tailored for maximum specific binding while simultaneously minimizing nonspecific adsorption. The second concept is based on polymers that are covalently attached to (oxide) surfaces. The preparation of these (end-) grafted functional polymers involves either the binding of preformed macromolecules to corresponding sites at the surface of the support or the recently introduced “grafting-from” method, by which an initiator molecule is first covalently bound to the surface and then activated — either by heat or light — in the presence of suitable monomer units such that a polymer chain grows from the solid/solution interface. Finally, the functionalization of patterned surfaces by peptide chains that mimic the binding domains of cell adhesion proteins is summarized. It is demonstrated that not only the selective adhesion of neuronal cells can then be controlled, but also their development with the outgrowth of dendrites and axons.     

Photocrosslinking of stilbene-modified polymers

The reactions of trans-2,5-dimethoxy-4′-aminostilbene with poly(maleic anhydride-co-methylvinyl ether) and trans-2,5-dimethoxy-4′-isocyanatostilbene with poly(oxy-1,4-phenyleneisopropylidene:1,4-phenyleneoxy-2-hydroxytrimethylene) yield polymeric systems which undergo rapid crosslinking upon short exposure to ultraviolet light. The extent of photocrosslinking as a function of exposure time was determined by the decrease of the trans-stilbene ultraviolet absorption at 350 nm.     

Compatibilization of inorganic particles for polymeric nanocomposites. Optimization of the size and the compatibility of ZnO particles

Summary The synthesis of in-situ hydrophobic functionalized ZnO nanoparticles via an emulsion process is systematically investigated. Different parameters are varied, such as precursor salt concentration and ultrasonification, to optimize the size and the size distribution of the ZnO particles. Particles with a size below 25 nm and surrounded by a hydrophobic polymer shell can be easily obtained. The influence of the polymeric shell on the compatibility with different polymeric matrices is described. Due to the small size of the inorganic particles and the excellent hydrophobization, highly transparent inorganic/organic nanocomposites can be obtained by spin-coating and extrusion.     

Gewissensfreiheit in der Apotheke

Background In recent years, it has been intensively debated whether and how the conscience must be protected in the context of pharmacies. Currently, Germany and Austria have no legal regulation regarding this problem. Objective The ethical framework for a coping strategy dealing with the problem of freedom of conscience in the pharmacy will be outlined. Method By applying legal ethics' principle of proportionality within German and Austrian constitutional law as well as the European Convention on Human Rights, the problem is analyzed on its individual, corporative, and societal level. Results On the individual level, the pharmacist's and the patient's stakes and rights (e.g., the freedom of conscience) are carefully balanced by using the principle of proportionality. On the corporative level, the autonomy granted by the fundamental right of freedom of religion and belief legitimatizes a pharmacy's ideological profile as an organization and may cause conflicts of loyalty within the pharmacy. On the societal level, four pro-active options of shaping the legal framework are available: a social-welfare, a libertarian, a professional, and a communitarian. How conflicts on the individual or the corporative level can be solved depends on the option(s) that are chosen on the societal level. Conclusion If the status quo is to be changed, this article argues for two approaches: a) the introduction of a qualified conscience clause for pharmacists (including duties to consult, refer, treat in emergencies, and inform); b) a ‘weak’ communitarian option, striving for a compromise between a pharmaceutical corporation (i.e., pharmacy or pharmaceutical professional association) with an ideological profile and the public healthcare system. Both approaches satisfy a careful balancing of legitimate goods.     

Transverse mixing and heat transfer in horizontal rotary drum reactors

The transverse mixing of quartz sand (mean particle sizes 157, 323, 794 and 1038 μm) and sodium carbonate (soda) (mean particle size 137 μm) has been investigated in a laboratory rotary drum reactor of 300 mm length and 310 mm diam. Solid movement in the drum was observed by means of colored tracers and successive exposures as well as by means of hot tracers and recording the local temperature in the bulk of particles. Three different types of the particles and bulk behaviour could be observed for stickly particles. The time constant of the mixing was estimated as a function of the rotational speed of the drum. The “cooling-down” curves of the bulk of particles were measured in a laboratory oven of 250 mm diam. and 600 mm length. The temperature variation as a function of the time can be described by the Newtonian cooling law, from which the heat transfer coefficient at the wall α_w was estimated.The absolute value of α_w's and their dependence on the contact time and particle diameter cannot be calculated by the heat penetration model, which disregards the film resistance at the bulk/wall contact. By taking into account this resistance a good quality of fitting can be achieved.