Thin Film Transistors (TFTs) are widely used in large area electronics because they offer the advantage of low cost fabrication and wide substrate choice. TFTs have been conventionally used for switching applications in large area display arrays. But when it comes to designing a sensor actuator system on a flexible substrate comprising entirely of organic and inorganic TFTs, there are two main challenges – i) Fabrication of complementary TFT devices is difficult ii) TFTs have a drift in their threshold voltage (VT) on application of gate bias. Also currently there are no circuit simulators in the market which account for the effect of VT drift with time in TFT circuits. The first part of this thesis focuses on integrating the VT shift model in the commercially available AIM-Spice circuit simulator. This provides a new and powerful tool that would predict the effect of VT shift on nodal voltages and currents in circuits and also on parameters like small signal gain, bandwidth, hysteresis etc. Since the existing amorphous silicon TFT models (level 11 and level 15) of AIM-Spice are copyright protected, the open source BSIM4V4 model for the purpose of demonstration is used. The simulator is discussed in detail and an algorithm for integration is provided which is then supported by the data from the simulation plots and experimental results for popular TFT configurations. The second part of the thesis illustrates the idea of using negative feedback achieved via contact resistance modulation to minimize the effect of VT shift in the drain current of the TFT. Analytical expressions are derived for the exact value of resistance needed to compensate for the VT shift entirely. Circuit to realize this resistance using TFTs is also provided. All these are experimentally verified using fabricated organic P-type Copper Phthalocyanine (CuPc) and inorganic N-type Tin doped Zinc Oxide (ZTO) TFTs. The third part of the thesis focuses on building a robust amplifier using these TFTs which has time invariant DC voltage level and small signal gain at the output. A differential amplifier using ZTO TFTs has been built and is shown to fit all these criteria. Ideas on vertical routing in an actual sensor actuator interface using this amplifier have also been discussed such that the whole system may be “tearable” in any contour. Such a sensor actuator interface can have varied applications including wrap around thermometers and X-ray machines.

Printing since many years has been a well-known high throughput technology for producing replications of graphic arts entities (texts, images, aesthetics, gloss and physical impressions) over large varieties of substrates which are dedicated for various needful applications like newspapers, magazines, posters, official documents, packages, braille, textiles, decorative articles and many more. Due to the fact, that printing is a liquid-solution based replication process, where basic ink and substrate are needed, it is now not only limited to printing of graphic arts. Whenever an ink is deposited over a defined substrate and the process can be multiplied, it can be termed as printing and once the final product contains a functionality other than graphic arts application, it can be called as “Printed Functionality”. Some examples for printed functionalities can be found in the following fields: A. Printed electronics (using inks having electronic properties); B. Printed micro-fluidics (using inks having polymeric and elastic properties for directive purposes); C. 3-Dimensional printing (using inks containing binding properties for developing three dimensional structures); D. Printed photonics (using inks having self-assembling properties for building-up symmetric micro-structures); E. Printed pyroelectrics (using inks containing thermally flammable properties); F. Printed ceramics (using inks with ceramic particles) and G. Printed optics and functional surfaces (using inks with transparency, absorbency and reflective properties). All these mentioned applications require functional inks which in turn exhibits some physical-chemical properties e.g. particle size, particle loading, fluid’s rheological properties etc. These properties determine the feasibility of the material’s deposition (in this case the functional inks) with a suitable printing technology. The inkjet printing technology among others has several advantages such as contactless deposition processability, digitalization (batch size one & turn-over time zero), user defined customization and adaptation, industrial relevance, minimal ink demand for R&Ds, freedom of substrate regularity and µm-scale print accuracy etc. Some of the imminent players in the inkjet printing technology market are Canon, Kodak, Hewlett Packard, Fujifilm Dimatix, Konica Minolta and XAAR. They provide print solutions from small to industrial scale printheads, printers, equipments and accessories for the realization of huge variety of application ideas. The inkjet is a versatile, but yet matured technology which finds its use in various application areas e.g. home office documentation, large format posters, variable data printing, security printing, textile printing, wallpapers, household articles, curved surfaces like bottles, printing over edible items, printing of elevated surfaces etc. And, hence there are several literatures published which show the use of the inkjet printing technology in the development of products for printed electronics. Some of the common examples are development of passive and active devices e.g. capacitors, resistors, thin-film-transistors, photovoltaics, sensors, circuits like logic gates for electronic switching, device arrays for detection purposes, point of care health applications, energy harvesting applications etc. But, the exploitation of the inkjet technology has not been intense enough to declare the industrial relevance of the technology to be utilized as a fabrication tool in the market. Meanwhile, all the researchers around the globe aim at a single goal, which is the development of “Proof of Concept” devices and applications. Thus, here in this dissertation the implementation of the inkjet printing technology as a digital fabrication tool is exploited to manufacture and up-scale the printed electronic products, which can show an industrial relevance to the commercial market. The main motivation why printed electronics is in great demand (scientific point of view) and has intensely emerged in the last decades, is because of the primary challenges faced in the fabrication process steps of the µ-electronics society. It is know that the classically fabricated µ-electronic products are in the market since long time due to their high reliability, consistent performance and defined applications in circuitry. But, what cannot be ignored is the involved fabrication steps promote several demerits such as the in-flexibility towards the fabrication process, material wastage, in-ability to up-scale into larger areas and huge quantities, and physical rigidity. Some of these mentioned problems are commonly seen e.g. spin coating, chemical vapor-phase deposition, physical vapor-phase deposition, atomic layer deposition and sputtering fabrication technologies. In this present dissertation, on the contrary, the challenges linked with the manufacturing process of the µ-electronic devices using the inkjet technology are focused and attempts are made to counteract them. Some of the foreseen challenges are: A. process workflow adaptation in device manufacturing; B. validation and evaluation of device performance; C. industrializing the inkjet technology (manufacturing µ-electronics in massive quantities); D. evaluating the fabrication yield of printed devices; D. Generating statistics regarding reliability and scalability; and E. demonstrating tolerances in electronic performances. These are definitely the challenges which must be overcome, and these key research points are addressed in the dissertation.