Ambient Light Organic Sensor in a Printed Complementary Organic TFT Technology on Flexible Plastic Foil

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Design and simulation of a high-gain organic operational amplifier for use in quantification of cholesterol in low-cost point-of-care devices

© The Institution of Engineering and Technology. This paper presents circuit design and simulations of a high gain organic Op-Amp, for use in quantification of real cholesterol, in the range of 1-9 mM. A 7-stage inverter chain is added onto the design so as to enhance the amplifier gain. The circuit adapts p-channel transistors only (PMOS) design architecture with saturated loads, simulated on a conventional platform, using appropriate OTFT model and associated parameters. The effect of variation in threshold voltage on circuit operation is also examined. For a supply voltage of ±15 V, the DC output voltage is found to be within an acceptable range of -1 V to -12.5 V, with a highest open loop gain of 83 dB. The closed loop gain is also in agreement with theoretical values, in the range of 1.5 dB to 39 dB, with corresponding bandwidths of 770 Hz to 275 Hz respectively. The latter gain of 39 dB and/or gain-bandwidth product of 10.63 kHz is currently the highest reported in the literature, for this lower supply voltage. The amplifier offers adequate quantification factor, with linear sensitivity of -0.7 V/mM. This paper is the first to adapt organic circuit designs in quantification of cholesterol, with promising outputs, for implementation in low-cost sensor systems

Design and simulation of a smart bottle with fill-level sensing based on oxide TFT technology

Packaging is an important element responsible for brand growth and one of the main rea-sons for producers to gain competitive advantages through technological innovation. In this re-gard, the aim of this work is to design a fully autonomous electronic system for a smart bottle packaging, being integrated in a European project named ROLL-OUT. The desired application for the smart bottle is to act as a fill-level sensor system in order to determine the liquid content level that exists inside an opaque bottle, so the consumer can exactly know the remaining quantity of the product inside. An in-house amorphous indium–gallium–zinc oxide thin-film transistor (a-IGZO TFT) model, previously developed, was used for circuit designing purposes. This model was based in an artificial neural network (ANN) equivalent circuit approach. Taking into account that only n-type oxide TFTs were used, plenty of electronic building-blocks have been designed: clock generator, non-overlapping phase generator, a capacitance-to-voltage converter and a comparator. As it was demonstrated by electrical simulations, it has been achieved good functionality for each block, having a final system with a power dissipation of 2.3 mW (VDD=10 V) not considering the clock generator. Four printed circuit boards (PCBs) have been also designed in order to help in the testing phase. Mask layouts were already designed and are currently in fabrication, foreseeing a suc-cessful circuit fabrication, and a major step towards the design and integration of complex trans-ducer systems using oxide TFTs technology

Flexible Ultralow-Power Sensor Interfaces for E-Skin

Thin-film electronics has hugely benefitted from low-cost processes, large-area processability, and multi-functionality. This has not only stimulated innovation in display and sensor technology, but has also demonstrated great potential for integration of components for human-machine interfaces. For electronics to be deployed as sensor interfaces and signal processing, the quest for low power is compelling due to the inherently limited battery lifetime. This review will present the state-of-the-art in thin film electronics and demonstrate examples of low-cost printable transistors and biosensors that are flexible/stretchable for wearable and other applications. Ultralow power design for thin-film transistors will be discussed from the standpoint of reducing both operating voltage and operating current, taking into account the challenges in meeting frequency requirements. Compact models for circuit design will be reviewed along with new insights into ultralow power transistors and high gain amplifier circuits. Finally, a concept for an integrated system comprising sensors and interfacing circuits will be demonstrated, which has the potential to enable battery-less operation.EPSRC under Project EP/M013650/1 EU under Projects DOMINO 645760, 1D-NEON 685758 and BET-EU 692373 IEEE Electron Devices Society PhD Student Fellowship China Scholarship Counci

Floor sensor development using signal scavenging for personnel detection system

"July 2010.""A Thesis Presented to The Faculty of the Graduate School At the University of Missouri--Columbia In Partial Fulfillment Of the Requirements for the Degree Master of Science."Thesis supervisor: Dr. Harry Tyrer.Falls have been a major cause of injuries likes fractures, head trauma in elder people. In many cases, these injuries have been fatal. This being a major concern of the Alzheimer's Association, a 'Smart Carpet' to detect a person's fall and accordingly generate an alarm was important. We developed faux floors and an actual floor for testing and demonstration to detect motion. We used a novel technique of signal scavenging to detect presence of the person. Aluminum foils were used as sensors as they were conducive to the applied pressure on them. Rigorous tests and experiments were performed on the faux floor sized 1m x 1m (3feet x 3feet) and 2.1m x 1m (7feet x 3feet) using these aluminum sensors. The noisy output pattern of the aluminum sensor was signal conditioned and converted into digital format using Op-Amps. The digital signal was later interfaced with a micro-controller unit and displayed onto a PC. Graphical analysis with ROC space and personal experience with utilization of the faux floor system gave us confidence to develop a real floor of the size 3.6m x 3.6m (12feet x 12feet). The results obtained on the full floor were beyond the expectations. Previously observed problems like cross-talk, noise interference and abrupt output behavior of the sensor system were avoided with careful manufacturing of carpet and earthing. With the development of the full floor, we have created a prototype which has high reliability and accuracy to detect motion and can be extensively used for further research.Includes bibliographical references (pages 57-59)

Investigation of Variation in Organic Thin-film Transistors (OTFT) and Design of Variation-aware Organic Circuits

This work investigates the key sources of variability in OTFT namely process variations and bias-stress induced variation, and presents circuit design techniques to build robust variation-aware digital and analog circuits using OTFT. OTFT suffer from a relatively large Vt variation due to the bias stress effects, and process mismatch variations. Though these effects are also prevalent in silicon based transistors, their magnitude is comparatively larger in the case of OTFT. This renders the well-established silicon based circuits unsuitable for organic electronics. Therefore, direct adaptation of the silicon based circuits for realising organic circuits does not effectively handle the relatively large parameter and mismatch variations associated with OTFT. In this work, we first investigate the bias-stress induced threshold voltage (Vt) variation and process variations to understand the impact of these variations on the performance of organic circuits. Then, two different strategies were employed to design robust organic circuits. The first method involves designing new load topologies that are more robust to the threshold voltage variations without compromising on gain. The other strategy was to realize the essential analog circuit functionalities like comparator, ADC using digital circuit blocks. In this direction, a digital comparator and digital A/D converter circuits were developed. Finally to demonstrate the system integration, a temperature sensing organic smart label system was designed