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The electrical performance of screen‐printed dry electrodes on thermoplastic polyurethane substrates are evaluated according to their conformance to international standards, skin‐electrode impedance, and ability to gather high quality electrocardiograms. The electrical behavior of seven screen‐printed electrodes (Ag, Ag/PEDOT:PSS, Ag/AgCl, Ag/AgCl/PEDOT:PSS, C, C/AgCl, and PEDOT:PSS) is compared to two commercially available gel electrodes (3M RedDot 50 and Philips NeoLead) which represent the state‐of‐the‐art. After basic standard electrical characterization (electrode‐electrode impedance, DC offset voltage, defibrillation recovery, bias stress, and noise), it is shown that layers like AgCl or PEDOT:PSS help to reduce the contact impedance of dry electrodes. However, the quality of the electrical signal is primarily governed by the skin impedance, which, without physical disruption or preparation, maintains a high impedance. For this reason, the impedance of all screen‐printed dry electrodes allows the collection of electrocardiograms with a quality equal to that of gel electrodes. Dry electrodes, while capable of obtaining similar electrical signal quality also bring the advantages of reusability, comfort, and the capability for long‐term measurements.

This paper reports on manufacturing and characterization of an all-solid-state potentiometric sensor aimed at monitoring pH in dialysate or blood plasma for patients who undergo dialysis. The sensing polymer-based membrane, coated on top of the Au working electrodes, contains a polymer matrix - poly(vinyl chloride), octadecyl isonicotinate as sensor molecule, plasticizer bis(2-ethyl hexyl) sebacate, and potassium-tetrakis(4-chlorophenyl) borate. The sensor was first calibrated over a wider pH interval, i.e. 5.0 - 9.0, and then for a pH interval which overlaps with the physiological pH, i.e. 7.0 - 8.0, followed by tests in human blood plasma. The response of the sensor is linear over the studied pH range, with a lifetime of two weeks and an accuracy of ∼ 0.08 pH. The response of the sensor is influenced by the storage conditions, and tests with sensors stored dry prior to potential measurements in buffers show that the sensor needs a few hours to reach an equilibrium, as opposed to seconds for the sensors stored in pH buffers prior to data collection. Monitoring the potential for 18 h continuously shows that the sensor does not drift. Toxicity and leaching of components from the sensor membrane into the liquid environment around it were studied, and determined which components were selected to further develop the pH sensor. © 2011 IEEE.

In this paper we present the use of Photonic Crystals as chemical sensors. These 2D nanostructured sensors were prepared by nano-imprint lithography during which a nanostructure is transferred from a nickel template into a responsive polymer, that is be specifically tuned to interact with the chemical compound that must be detected. By creating a Photonic Crystal in a responsive polymer, the sensitivity of such a sensor can be greatly enhanced with respect to nanophotonic sensors that are only functionalized by a surface treatment. We have shown the functionality of an imprinted sensor by exposing the nanostructures to various liquids and vapours and monitor the change in reflected signal. Depending on the interactions and refractive index contrasts, the maximum wavelength of the reflected light can decrease (when exposed to toluene) or increase (when exposed to acetone). © 2011 Published by Elsevier Ltd.

A distributed chemical sensor is developed by coating multiple Bragg gratings in a single glass fiber with chemical responsive coatings. The composition of the coating is tuned to the target chemicals to be measured and the optical response of the coated grating is optimized by changing the coating thickness. Specific recoaters were used to apply the responsive coatings reproducibly onto the glass fibers. The coating compositions can be based on UV curing or solvent based systems. In this paper we show the development and application of a distributed gas sensor for CO 2 , H 2 S and H 2 O that can be used for down-hole monitoring in the oil and gas industry. We have developed a toolbox for the design and modeling of the responsive polymer coatings, and the performance of the actual sensors corresponded well with the predicted behavior.

A study on via drilling and channel scribing on PEN and PET substrates for flexible electronic application is discussed in this paper. For the experiments, both KIF excimer laser (248 nm) and frequency tripled Nd:YAG (355 nm) laser are used. Different measurement techniques like optical microscopy, Dektak profilometer, Confocal microscopy and scanning electron microscopy (SEM) were employed to characterize the quality of the channels and vias. The patterned structures were filled by three different methods using a conductive paste or ink that is cured in an oven at an elevated temperature. The cross-sectional measurements of channels and vias were carried out using SEM to study the uniformity of filling.

The soft lithographic replication of patterns with a low filling ratio by microcontact printing (microCP) is problematic due to the poor mechanical stability of common elastomeric stamps. A recently described strategy to avoid this problem employs a modified patterning method, positive microcontact printing ((+)microCP), in which a stamp with a mechanically more stable inverted relief pattern is used. In contrast to conventional negative microCP ((-)microCP), in the contact areas a self-assembled monolayer (SAM) is printed of a "positive ink", which provides only minor etch protection, whereas the noncontacted areas are subsequently covered with a different, etch-resistant SAM, prior to development by chemical etching. With the aim to identify novel, highly versatile positive inks, the patterning of gold by (+)microCP with mercaptoalkyloligo(ethylene glycol)s (MAOEGs), the subsequent adsorption of octadecanethiol (ODT), and the final development by wet chemical etching have now been studied. A polydisperse mixture of mercaptoundecylocta(ethylene glycol) derivatives was found to provide the best patterning results. The surface spreading of the positive ink during stamping, the exchange of printed MAOEGs with ODT, and the choice of the right etching bath were identified as key parameters that influence the achievable pattern resolution and contrast. Due to the modular composition of functionalized alkyloligo(ethylene glycol) derivatives, (+)microCP with these positive inks has the potential for easy adaptation to a variety of materials and development conditions.