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In this contribution, a conformable 64×45 RGB light-emitting diode (LED) matrix is presented. A design concept of stretchable electronics is used: non-stretchable polymer islands host rigid LEDs and are interconnected by horseshoe shaped metallic conductors, which are able to deform together with an elastomeric substrate. Thin-film metallization is used to enable a pixel pitch of 1 mm, while polyimide is used to realize the non-stretchable islands, but also to support the meandering conductors. The design of the stretchable interconnections has been optimized with respect to their mechanical and electrical performance. Thermoplastic polyurethane is introduced at a final stage of the fabrication process to ensure its compatibility with conventional thin-film processing. A passive matrix addressing scheme is used to drive the LED matrix. At a supply voltage of 10 V, the brightness of the display reaches up to 700 cd/m2.

In this paper, we demonstrate a scalable and low-cost memory technology using a phase separated blend of a ferroelectric polymer and a semiconducting polymer as data storage medium on thin, flexible polyester foils of only 25μm thickness. By sandwiching this polymer blend film between rows and columns of metal electrode lines where each intersection makes up one memory cell, we obtained 1 kbit cross bar arrays with bit densities of up to 10 kbit/cm2. © 2014 The Japan Society of Applied Physics

In this paper, we successfully fabricated and operated passive matrix P(VDF-TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium-Gallium-Zinc-Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF-TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ∼105 with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ∼10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future. © 2013 Elsevier B.V. All rights reserved.

Sensors integrated into food packages could benefit consumers by ensuring freshness and quality while allowing retail industry to more efficiently manage food stocks and product authenticity. Here we present smart radio-frequency labels with sensors able to measure temperature, humidity and the presence of volatile amine compounds. The labels are made via high quality screen printing and lamination technologies on low cost foils in combination with pick and place technology. As a case study the smart labels are used to quantify the freshness of fish.

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement. © 2009 American Chemical Society.

Sensors based on organic electronic devices are emerging in a wide range of application areas. Here we present a sensor platform using organic light emitting diodes (OLED) and organic photodiodes (OPD) as active components. By means of lamination and interconnection technology the functional foils with OLED and OPD arrays form an in-plane optical sensor platform (IPOS). This platform can be extended with a wireless data and signal processing unit yielding a sensor node. The focus of our research is to engage the node in a healthcare application, in which a bandage is able to monitor the vital signs of a person, a so-called Smart Bandage. One of the principles that is described here is based on measuring the absorption modulation of blood volume induced by the pulse (photoplethysmography). The information from such a bandage could be used to monitor wound healing by measuring the perfusion in the skin. The OLED and OPD devices are manufactured on separate foils and glass substrates by means of printing and coating technologies. Furthermore, the modular approach allows for the application of the optical sensing unit in a variety of other fields including chemical sensing. This, ultimately enables the measurement of a large variety of physiological parameters using the same bandage and the same basic sensor architecture. Here we discuss the build-up of our device in general terms. Specific characteristics of the used OLEDs and OPDs are shown and finally we demonstrate the functionality by simultaneously recorded photoplethysmograms of our device and a clinical pulseoximeter.

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

The introduction in the market of ubiquitous sensing applications relies heavily on the availability of affordable sensors. Key in the cost of a sensor is its modus of manufacture. In this paper a sensing scheme is presented, in which the signal transduction is based on an induced change in the optical path between an organic light emitting diode (OLED) and an organic photovoltaic (OPV) array. Using this platform, several aspects of cost efficient manufacturing technology are investigated. These aspects include the intrinsic printability of the active (OLED, responsive coating and OPV) components, which allows control of the local sensor functionality and sensitivity. It offers a large amount of freedom in sensor layout, while using relatively few process steps. Also investigated is the ability to realize the active devices on foil, which enables high throughput processing (e.g. in a reel-to-reel scheme). Moreover, the presented generic sensing scheme is of a modular design. It allows easy switching of the sensor functionality mostly by simply changing the transduction module. Since this does not affect the production parameters of the other components, these may be standardized, thus invoking favorable economies of scale.