Ultra Low-Cost RFID design using Organic Field Effect Transistor on Plastic Substrate
The development of ultra-low cost printed Organic Field Effect Transistor (OFET) for RFID (Radio Frequency Identification), operating in high frequency (HF) range (13.56 MHz) has been studied in this paper. For high frequency operation N/P type OFETs must have the mobility greater than 8 cm2/Vs, and channel length in the orders of micrometres and operating potential in the orders of 3 V. The OFET when processed on the plastic substrates would practically eliminate the fragile silicon wafer, which introduces flexibility in the integrated circuits.
The OFET will dramatically revolutionized the current RFID market with all-printed continuous roll to roll and flexible printed circuits and individual tags, costing only few cents. Fabrication an OFET on the plastic substrate must performed in very low temperatures (lower than 300 °C) applying novel fabrication techniques. Nanoparticles rather than bulk conducting materials could be used as the interconnections for the RFID circuit development on the plastic surface. For very high mobility purest form of organic semiconductors (P or N type organic materials) have to be created. Finally, passive components like inductors, capacitors and interconnections must be fabricated on the same plastic substrate to get the printed RFID circuit system.
Figure (1): Basic design of a RFID tag. (From PolyIC GmbH)
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Analysis of sub-wavelength grating in Opti FDTD Simulator
Standard sub-wavelength grating array is designed and 2D simulation is carried out, on OptiFDTD 8.0 simulation software. Implementation of different types of sub-wavelength grating are discussed and analyzed with simulation results. The power transmittance at different wavelength under the variation of different grating parameters is demonstrated on the simulation. Grating periods (K), grating spacing (d), grating material and the presence of substrate are the parameters varied for the transmittance analysis and also effects of the parameters on power transmittance are studied. Finally, profound analysis of the results is done to have better understanding of sub-wavelength gratings.
Figure (1): Optical grating present in the air.
Figure (2): Power transmittane (T) calculation with certain path length (w).
where, Tlais the power transmittance at certain wavelength (la). a is the absorption coefficient and w is the path length.
Figure (3): Variation of Power transmittance with different grating periods (K-nm) but with same spacing (d = 250 nm), measured at different wavelengths (nm).
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Cellphone Operated Robotic Assistant
The aim of the project is to design and implement ' a robotic system consisting of a robotic arm mounted on a mobile platform'. The robot is controlled with the help of a mobile phone. The calling phone sends a Dual Tone Multi-Frequency (DTMF) tone to the receiving phone. The output from the receiving cellphone is fed to a DTMF decoder chip which gives binary output to the microcontroller. The microcontroller is pre-programmed to send the output bits according to the input bits it receives. These bits are then given as Pulse Width Modulated (PWM) input to the three servo motors and binary inputs to a DC motor driver IC which runs the two DC motors.
The two DC motors are attached to the two rear wheels of the mobile platform, which is in the form of a land rover, capable of standard locomotion in all directions. The three servo motors are connected to the links of the robotic arm which resembles the human arm, and is designed to have three degrees of freedom. Thus, in all, five motors are controlled by a single cellphone which is capable of providing 12 controls. Variable levels of automation may be attributed to the robot by suitably modifying the programming of the mounted microcontroller chip.
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