This PDF file contains the front matter associated with SPIE Proceedings Volume 7779, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq₃, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCER^R layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.

We have successfully manufactured rubber-like large-area stretchable integrated circuits comprising printed elastic conductors, organic transistor-based circuits, and silicon transistor-based circuits. Employing the first direct integration of organic and silicon (Si) integrated circuits, we have realized to develop a stretchable electromagnetic interference (EMI) measurement sheet that can detect EMI distribution on the surface of electronic devices by wrapping the devices in the sheet. The stretchable devices can spread over arbitrary surfaces including free-formed curvatures and movable parts, thereby significantly increasing the applications of electrical circuits.

An all polymeric colorimetric gas sensor with its associated electronics for ammonia (NH₃) detection targeting low-cost and low-power applications is presented. The gas sensitive layer was inkjet printed on a plastic foil. The use of the foil directly as optical waveguide simplified the fabrication, made the device more cost effective and compatible with large scale fabrication techniques, such as roll to roll processes. Concentrations of 500 ppb of NH₃ in nitrogen with 50% of RH were measured with a power consumption of about 868 μW in an optical pulsed mode of operation. Such sensors foresee applications in the field of wireless systems, for environmental and safety monitoring. The fabrication of the planar sensor was based on low temperature processing. The waveguide was made of PEN or PET foil and covered with an ammonia sensitive layer deposited by inkjet printing, which offered a proper and localized deposition of the film. The influence of the substrate temperature and its surface pretreatment were investigated to achieve the optimum deposition parameters for the printed fluid. To improve the light coupling from the light source (LED) to the detectors (photodiodes), polymeric micro-mirrors were patterned in an epoxy resin. With the printing of the colorimetric film and additive patterning of polymeric micro-mirrors on plastic foil, a major step was achieved towards the implementation of full plastic selective gas sensors. The combination with printed OLED and PPD would further lead to an integrated all polymeric optical transducer on plastic foil fully compatible with printed electronics processes.

Microdosimetry describes the energy deposition of ionizing radiation on a microscopic scale by quantifying how Linear Energy Transfer (LET) of any radiation type creates local biological or physical damage sites. It thus provides a model of damage on a molecular level (DNA). Microdosimetry characterizes cellular effects and is used for understanding radiation oncology and human exposure. Ideal detectors for these applications have the same physical size and radiation cross section as a (human) cell. That cross section is a strong function of its composition, density, and the incident radiation's quality. Consequently, an organic, nano/micro radiation sensor is highly desirable. Ideal materials for these devices have a high mobility, small carrier trapping times, high resistivity, and unit density. Devices produced from these materials would be "tissue equivalent." We present a solid state tissue equivalent detector using an organic semiconductor as the active region. Many of the difficulties associated with ultrahigh resistance devices are eased by our novel geometric approach. We present the design of a detector with an organic active region, effective solutions to the materials problems, and device responses to radiation.

Aside from other target applications, organic field-effect transistors (OFETs) are also promising devices for sensing various kinds of analytes, including gases, ions and biomolecules. In this work ion-sensitive polymer-based OFETs will be discussed. In detail, operational device instabilities caused by the movement of mobile ions in poly(3-hexylthiophene)-based OFETs are investigated, when (a) an ion-containing gate dielectric, polyvinyl alcohol (PVA), is applied in a top-gate architecture and (b) ions are deliberately added to the organic semiconductor in a bottom-gate architecture. The underlying mechanisms for the observed source-to-drain channel current drifts upon bias stress are thoroughly explained. In addition, device instabilities due to mobile ions within the dielectric are demonstrated with rigid and flexible PVA-based OFETs including inkjet-printed source/drain electrodes and a meander-shaped top-gate architecture, the latter enabling the realization of smart, integrated and low-cost OFET-based sensor systems.

We report the fabrication of carbon nanotube field-effect transistors for biosensing applications and the development of protocols for reliable protein and DNA sensing. The sensing method we employ is 'label free', relying only on the intrinsic charge of the biological molecule of interest. We discuss fabrication issues that we have solved, for example the preparation of clean surfaces, and the sensing protocol issues that we have encountered. Polylysine and ss-dna, highly charged biological molecules, are used as model systems to illustrate the performance of our biosensors.

Luminescent conjugated polymers (LCPs) have been frequently utilized for optical biosensors. The detection schemes of these sensors are employing the light harvesting properties or the conformation sensitive optical properties of the conjugated polymers. LCPs have been utilized as colorimetric and fluorescent sensing elements for the recording of biological processes. However, LCPs have several limitations for being used as real time in vivo imaging agents. In this regard, novel thiophene based molecular scaffolds, denoted luminescent conjugated oligothiophenes (LCOs) have been developed. These LCOs are chemically defined molecules having distinct side chain functionalizations and a precise number of thiophene units. Herein the utilization of LCOs as specific ligands for the pathological hallmarks underlying protein misfolding diseases, such as Alzheimer's disease, is described. The use of the conformation sensitive optical properties of the LCOs for spectral separation of these pathological entities in a diversity of in vitro, ex vivo or in vivo systems is demonstrated. The protein aggregates are easily identified due to the conformation-dependent emission profile from the LCOs and spectral assignment of protein aggregates can be obtained. Overall, these probes will offer practical research tools for studying protein misfolding diseases and facilitate the study of the molecular mechanism underlying these disorders.

Here we report on the fabrication and detailed characterization of flexible low-voltage organic thin-film transistors directly integrated with pyro- and piezoelectric sensors. The functional layer of the capacitive sensors is a ferroelectric fluoropolymer. The transistors on the other hand are based on a high-k nanocomposite gate dielectric and on pentacene as the organic semiconductor and can be operated well below 5V. It is shown, that the transistors can be fabricated on the fluororpolymer layer. Since the control of parameter spread is a very important topic in large area electronics, it was attempted to investigate the homogeneity of a significant set of devices by individual assessment of the layer composition and thickness, the pentacene morphology, the actual geometry and the electrical parameters. It turned out that starting from the measured device parameters such as layer thickness, capacitance, channel dimension, grain size and threshold voltage, the drain current can be calculated with high accuracy in a specified operation point. In addition, it is shown that the main influence on the parameter spread originates from the variations in the threshold voltage. Storage in air destroys the transistors on the long term, whereas bias stress measurements under inert conditions reveal that the interfaces are very stable.

Recent advances toward commercialization of a new generation of low-cost LED- and OLED-based monitors for dissolved oxygen (DO), and multiple (bio)analytes such as glucose, lactate, alcohol, and cholesterol are described. The design of the DO monitors, which contain no optical fibers, filters, mirrors, or lens, is significantly simpler and consequently lower-cost than that of commercial LED-based DO monitors. The multiple (bio)analyte monitors are based on a DO monitor and the oxidase enzyme specific to each analyte. The potential advantages and disadvantages of the OLED- vs LED-based monitors is also discussed.

The synthesis and photosensing ability of a novel green-absorbing dendrimer are presented. The photoresponse of a photodiode comprising a bulk heterojunction blend of a first generation ketocyanine-cored dendrimer with carbazole dendrons and fluorenyl surface groups and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) shows good spectral selectivity for digital camera applications. The narrow absorbing photodiode achieved an external quantum efficiency of 2.9% at 515 nm and maintained a profile similar to the absorption of the unblended dendrimer.