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The work describes a fast and flexible micro/nano fabrication and manufacturing method for ceramic Micro-electromechanical systems (MEMS)sensors. Rapid prototyping techniques are demonstrated for metal oxide sensor fabrication in the form of a complete MEMS device, which could be used as a compact miniaturized surface mount devices package. Ceramic MEMS were fabricated by the laser micromilling of already pre-sintered monolithic materials. It has been demonstrated that it is possible to deposit metallization and sensor films by thick-film and thin-film methods on the manufactured ceramic product. The results of functional tests of such manufactured sensors are presented, demonstrating their full suitability for gas sensing application and indicating that the obtained parameters are at a level comparable to those of industrial produced sensors. Results of design and optimization principles of applied methods for micro- and nanosystems are discussed with regard to future, wider application in semiconductor gas sensors prototyping.
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Today, electrochemical sensors are used for a broad range of applications. A fundamental challenge is still the achievement of long-term sensor stability by ensuring good adhesion between the deposited sensing layer and the substrate material, e.g., a metal electrode. Until now, the most applied strategy to overcome this problem is to increase the surface roughness of the metal layer by mechanical etching or by electroplating of additional material layers, which both imply an increase in manufacturing steps and thus the final cost of the overall device. Alternatively, to overcome these adhesion problems, we propose the direct printing of a novel platinum nanoparticle ink, which is compatible with low-cost additive digital inkjet and with flexible low-cost substrates. This water-based platinum ink has two unique features: it leads to highly rough surfaces, which promotes the adhesion of deposited sensing material, and it is a highly low-temperature curing ink, compatible with polymeric substrates that cannot withstand high temperatures. Based on this concept, we report about a long-term stable and highly sensitive solid-state pH sensor functionalized by anodic electrodeposited iridium oxide on a rough nanostructured platinum printed layer. The sensors showed an excellent reproducibility with a linear super-Nernstian response (71.3 ± 0.3 mV/pH unit) in a wide pH range (pH 2-11). Long-term stability tests for over 1 year of application demonstrate an excellent mechanical sensor layer stability, which is correlated to the distinct roughness of the printed platinum layer. This novel approach is useful to simplify the fabrication process and with that the sensor costs.
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BACKGROUND: The aim of the prospective Homburg Cream and Sugar study was to analyze the role of fasting and postprandial serum triglycerides (TG) as risk modifiers in patients with coronary artery disease (CAD). METHODS AND RESULTS: A sequential oral triglyceride and glucose tolerance test was developed to obtain standardized measurements of postprandial TG kinetics and glucose in 514 consecutive patients with stable CAD confirmed by angiography (95% were treated with a statin). Fasting and postprandial TG predicted the primary outcome measure of cardiovascular death and hospitalizations after 48 months follow-up (fasting TG >150 vs. <106 mg/dl: Hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.31-2.45, p = 0.0001; area under the curve >1120 vs. <750 mg/dl/5 hr: HR 1.78, 95% CI 1.29-2.45, p = 0.0003). Parameters of the postprandial TG increase did not improve risk prediction compared to fasting TG. The number of cardiovascular deaths and myocardial infarctions was higher in the upper tertile of fasting TG (HR 1.79, 95%-CI 1.04-3.09, p = 0.03). Risk prediction by TG was independent of traditional risk factors, medication, glucose metabolism, LDL- and HDL-cholesterol. Total cholesterol, LDL- and HDL-cholesterol concentrations were not associated with the primary outcome. CONCLUSIONS: Fasting serum triglycerides >150 mg/dl independently predict cardiovascular events in patients with coronary artery disease on guideline-recommended medication. Assessment of postprandial TG does not improve risk prediction compared to fasting TG in these patients.