Silicon-based digital electronics have evolved over decades through an aggressive scaling process following Moore's law with increasingly complex device structures. Simultaneously, large-area electronics have continued to rely on the same field-effect transistor structure with minimal evolution. This limitation has resulted in less than ideal circuit designs, with increased complexity to account for shortcomings in material properties and process control. At present, this situation is holding back the development of novel systems required for printed and flexible electronic applications beyond the Internet of Things. In this work we demonstrate the opportunity offered by the source-gated transistor's unique properties for low-cost, highly functional large-area applications in two extremely compact circuit blocks. Polysilicon common-source amplifiers show 49 dB gain, the highest reported for a twotransistor unipolar circuit. Current mirrors fabricated in polysilicon and InGaZnO have, in addition to excellent current copying performance, the ability to control the temperature dependence (degrees of positive, neutral or negative) of output current solely by choice of relative transistor geometry, giving further flexibility to the design engineer. Application examples are proposed, including local amplification of sensor output for improved signal integrity, as well as temperature-regulated delay stages and timing circuits for homeostatic operation in future wearables. Numerous applications will benefit from these highly competitive compact circuit designs with robust performance, improved energy efficiency and tolerance to geometrical variations: sensor front-ends, temperature sensors, pixel drivers, bias analog blocks and high-gain amplifiers.

The use of physical paper is often preferred due to its unique physical properties that improve various aspects of reading. However, digital media and information are more engaging, diverse, and up to date, thereby challenging the existence of paper in our everyday life. By combining the two types of media in a seamless way, the interactivity of multimedia content can complement the reading experience, maintaining the unique feel of paper books. The current state of the art addressing this application negatively impacts the reading experience and often does not consider the manufacturability and sustainability of the proposed solutions. Herein, the Magic Bookmark, a technical solution for automatically recognizing the open page of a physical book, to provide seamless augmentation without changing the user's behavior and experience significantly is introduced. Three alternative solutions are implemented, with various degrees of ease of use, manufacturability at scale, and reliability of data reading. The optimal realization is found to be a reflective optical readout array, for which routes to implementation that may allow blending the graphical and functional aspects of the augmented book are proposed.

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A new form of interaction with digital displays is described, using the pages and binding of a physical book as the interface. This leads to a form of augmented book, or a-book, which can seamlessly trigger multimedia content on a nearby device using embedded light, pressure or touch sensors.

Paper books offer a unique physical feel, which supports the reading experience through enhanced browsing, bookmarking, freeform annotations, memory and reduced eye strain. In contrast, electronic solutions, such as tablets and e-readers, offer interactive links, updatable information, easier content sharing, and efficient collaboration. To combine the best aspects of paper and digital information for reading, we demonstrate two mechanisms for augmenting paper with light sensors that trigger digital links on a nearby smartphone. Light Tags on every page of a book are used in a first demonstration to identify which pages are open. These are replaced with an electronic Magic Bookmark in a second demonstration, avoiding the need to instrument every page. CCS CONCEPTS • HardwareàCommunication hardware, interfaces and storageàSensor devices and platforms • Human-centered computingàHuman computer interaction (HCI)àInteraction devices

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Printing techniques have been widely adopted in the fabrication of flexible electronic components. However, its application is still limited in complex control and communication circuitry due to the low performance and low fabrication uniformity amongst printed devices, compared to conventional electronics. Thus, the electronic systems in real-world applications are hybrid integrations of printed and conventional electronics. Here we demonstrate a low-cost, low-complexity, fully-printable flexible photodetector that can withstand over 100 1 mm-radius bending cycles using a simple and scalable two-step fabrication process. The prototypes are implemented in an augmented book system to automatically detect the ambient light through optical apertures on paper of a printed book, and then transmit the information to an adjunct device. This technique demonstrates the utility of low-cost materials and processes for robust large area sensing applications and could act as a gateway to pertinent multimedia information.

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