Embedded Linux based demonstration device for printed electronics

As use of printed electronics is going towards expansion in near future, researchers are studying methods for development of printed components, and also procedures for driving them. Few low speed but low cost, and flexible stand alone systems e.g., some sensor systems and displays; have already made their way to market after competing conventional, high speed, high cost, and rigid silicon electronics. At present, there are different type of printed sensors and display matrices, which have been developed but not being used in stand alone systems. Thus, there was a need for demonstrating ‘developed printed electronic components’ in such a way, that they are integrated with other core electronic circuits like embedded systems, to assure their ability to replace individual conventional component. In the thesis, some experiments were conducted to drive printed electronic components while overlooking their manufacturing details; i.e., the circuit used to drive the printed components was not a part of printed technology (e.g., printed processing, memory units), rather a conventional system (e.g., microcontroller and microprocessor boards available in market) is used. Particularly for this project the printed components are meant to be capacitive sensor matrix, resistive touch screen, organic light emitting diodes (OLED) matrix, electrophoretic display matrix, and electrochromic display matrix. These components were interfaced using embedded system in such a way that they can be driven meaningfully e.g., resistive touch screen can control display option for OLED matrix. Embedded Linux has significant advantages over previously used OS and non-OS based solutions as it is robust, scalable, and manage resources efficiently. Such a system with backbone of Linux processing was a part of design, which handled a separately designed interface board capable of interfacing 13 capacitive sensor (maximum 8 pF) inputs, a four wire resistive touch screen (with few hundred ohm resistance between terminals), a current driver with 50 mA segment current for 10 x 10 display matrix and voltage range from 0 to 5 V, voltage driver for two led segments capable of dissipate 40 mA at 5 V, finally a voltage driver for separate 10 led segments capable of dissipating 40 mA from 0 to 15 V or a 10 x 10 display matrix with power rating of maximum 16.9 mA at 0 to 15V. So, in this way different displays or individual led segments can be interfaced with a system which can download their display configuration from HTTP client based user interface, and upload the capacitive sensor and resistive touch screen readings back to user. The device was capable of changing demonstration parameters e.g., blinking, animation for displays via user interface, and program structure was kept convertible so that minor changes can create completely new demonstration: interfacing different components. Design included a power board capable of providing stable 1A supply current at 5V. A Current-Voltage (I-V) characterizing board was part of design which can measure I-V curve of printed solar cells. Printed electronic components were interfaced with embedded systems without much problem, making one comfortable in conclusion that these individual components are ready to replace conventional components in non-standalone systems at-least.