Synthesis of multifunctional plasmonic nanopillar array using soft thermal nanoimprint lithography for highly sensitive refractive index sensing.

A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated.

Methacrylate Copolymers with Liquid Crystalline Side Chains for Organic Gate Dielectric Applications.

Polymers for all-organic field-effect transistors are under development to cope with the increasing demand for novel materials for organic electronics. Besides the semiconductor, the dielectric layer determines the efficiency of the final device. Poly(methyl methacrylate) (PMMA) is a frequently used dielectric. In this work, the chemical structure of this material was stepwise altered by incorporation of cross-linkable and/or self-organizing comonomers to improve the chemical stability and the dielectric properties. Different types of cross-linking methods were used to prevent dissolution, swelling or intermixing of the dielectric e.g. during formation processes of top electrodes or semiconducting layers. Self-organizing comonomers were expected to influence the dielectric/semiconductor interface, and moreover, to enhance the chemical resistance of the dielectric. Random copolymers were obtained by free radical and reversible addition-fragmentation chain transfer (RAFT) polymerization. With 6-[4-(4'-cyanophenyl)phenoxy]alkyl side chains having hexyl or octyl spacer, thermotropic liquid crystalline (LC) behavior and nanophase separation into smectic layers was observed, while copolymerization with methyl methacrylate induced molecular disorder. In addition to chemical, thermal and structural properties, electrical characteristics like breakdown field strength (EBD) and relative permittivity (k) were determined. The dielectric films were studied in metal-insulator-metal setups. EBD appeared to be strongly dependent on the type of electrode used and especially the ink formulation. Cross-linking of PMMA yielded an increase in EBD up to 4.0 MV/cm with Ag and 5.7 MV/cm with PEDOT: PSS electrodes because of the increased solvent resistance. The LC side chains reduce the ability for cross-linking resulting in decreased breakdown field strengths.

Determination of the wine preservative sulphur dioxide with cyclic voltammetry using inkjet printed electrodes.

During winemaking sulphur dioxide is added to prevent undesirable reactions. However, concerns over the harmful effects of sulphites have led to legal limits being placed upon such additives. There is thus a need for simple and selective determinations of sulphur dioxide in wine, especially during winemaking. The simultaneous detection of polyphenols and sulphur dioxide, using cyclic voltammetry at inert electrodes is challenging due to close oxidation potentials. In the present study, inkjet printed electrodes were developed with a suitable voltammetric signal on which the polyphenol oxidation is suppressed and the oxidation peak height for sulphur dioxide corresponds linearly to the concentration. Different types of working electrodes were printed. Electrodes consisting of gold nanoparticles mixed with silver showed the highest sensitivity towards sulphur dioxide. Low cost production of the sensor elements and ultra fast determination of sulphur dioxide by cyclic voltammetry makes this technique very promising for the wine industry.

Food intake monitoring: automated chew event detection in chewing sounds.

The analysis of the food intake behavior has the potential to provide insights into the development of obesity and eating disorders. As an elementary part of this analysis, chewing strokes have to be detected and counted. Our approach for food intake analysis is the evaluation of chewing sounds generated during the process of eating. These sounds were recorded by microphones applied to the outer ear canal of the user. Eight different algorithms for automated chew event detection were presented and evaluated on two datasets. The first dataset contained food intake sounds from the consumption of six types of food. The second dataset consisted of recordings of different environmental sounds. These datasets contained 68,094 chew events in around 18 h recording data. The results of the automated chew event detection were compared to manual annotations. Precision and recall over 80% were achieved by most of the algorithms. A simple noise reduction algorithm using spectral subtraction was implemented for signal enhancement. Its benefit on the chew event detection performance was evaluated. A reduction of the number of false detections by 28% on average was achieved by maintaining the detection performance. The system is able to be used for calculation of the chewing frequency in laboratory settings.

Biologically inspired omniphobic surfaces by reverse imprint lithography.

Springtail skin morphology is translated into robust omniphobic polymer membranes by reverse imprint lithography. The combination of overhanging cross-sections and their arrangement in a self-supporting comblike pattern are crucial for mechanically stable coatings that can be even applied to curved surfaces.

Food intake monitoring: an acoustical approach to automated food intake activity detection and classification of consumed food.

Obesity and nutrition-related diseases are currently growing challenges for medicine. A precise and timesaving method for food intake monitoring is needed. For this purpose, an approach based on the classification of sounds produced during food intake is presented. Sounds are recorded non-invasively by miniature microphones in the outer ear canal. A database of 51 participants eating seven types of food and consuming one drink has been developed for algorithm development and model training. The database is labeled manually using a protocol with introductions for annotation. The annotation procedure is evaluated using Cohen's kappa coefficient. The food intake activity is detected by the comparison of the signal energy of in-ear sounds to environmental sounds recorded by a reference microphone. Hidden Markov models are used for the recognition of single chew or swallowing events. Intake cycles are modeled as event sequences in finite-state grammars. Classification of consumed food is realized by a finite-state grammar decoder based on the Viterbi algorithm. We achieved a detection accuracy of 83% and a food classification accuracy of 79% on a test set of 10% of all records. Our approach faces the need of monitoring the time and occurrence of eating. With differentiation of consumed food, a first step toward the goal of meal weight estimation is taken.

Wireless long-term ECG integrated into clothing.

The integration of electronic devices into clothing to monitor biosignals is demonstrated with the integration of a 3-channel ECG device into a shirt. It is shown that several basic requirements concerning the electronic design must be fulfilled, exceeding the capabilities of conventional portable systems. The application of flexible connection and housing technologies is addressed in the present paper. Printed boards should be flexible enough to adapt to movements of the human body. Small size as well as water-resistant or even washable construction is required. Additional points concern replacing the disturbing loose cable connections with a more integrated solution. A long period of operation without recharging the battery, uploading the data or changing the electrodes has to be achieved. The system should feature an uninterrupted 7-day operation period known as 24/7-monitoring regime. Starting with its specification, the basic design of the prototype is presented. First investigations have shown the washability of the shirt together with the inserted electronics.