Academic Projects

Fabrication and characterization:

• Single-anchored (cantilever) and double-anchored (bridge) MEMS actuators / switches.

Fabrication and electrical characterization of single-anchored (cantilever) and double-anchored (bridge) MEMS actuators (switches). Mechanical structure was fabricated by growing 100nm titanium (Ti) and 800nm gold (Au) successive layers on 1.8cm × 1.8cm silicon wafer. Devices with various structural parameters were fabricated and electrically characterized. It was compared to standard theoretical models and the reason of deviation was investigated. Mechanical structure with 100 nm Ti and 800 nm Au successive layers on 1.8 X 1.8 sq. cm Si wafer.

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• Basic electronic devices on <111> silicon wafer.

Fabrication and electrical characterization of (1) p-MOSFETs of different channel length, channel width, oxide thickness, and channel doping concentration, (2) p-n Diodes of different active areas, (3) Different types of Diffusion Resistors - Van der Pauw structure, transmission line structure, and Serpentine structure, and (4) MOS Capacitors of different area and oxide thicknesses. Fabrication was done on a silicon wafer with <111> crystal orientation and initial donor concentration of 1e15 per cubic cm.

Electrical characterization were done on each device, parameters such as threshold voltage, subthreshold slope, breakdown voltage, reverse saturation current etc were extracted. Measured quantities were compared to standard theoretical models and deviation was investigated in terms of fabrication non-idealities.

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Design and hardware implementation:

• Wireless ECG Monitoring System.

ECG signal is collected and amplified. The common mode noise is taken as reference to avoid signal fluctuation. The signal is primarily filtered using hardware high pass filter to eliminate the noise coming from signal sources. The analog signal is converted to digital signal considering Nyquist criterion using ADC of a microcontroller, which further processed the digital data and transmitted it wirelessly through a RF transmitter chip. The synchronized receiver end receives the data and passes it to computer. Computer collects the data for certain period of time, filters it successively and displays it on screen. The analysis on computer was done using MATLAB. The computer also compresses the data using a novel technique and stores it (see published paper) .

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• Temperature & Humidity Monitoring System.

Temperature and Humidity was sensed using sensors and collected as electric signals. The analog electrical signals were converted to digital using ADC of microcontroller. The digital data was transmitted using RF transmitter. The synchronized receiver collects the data and saves it to a temporary memory (register) which is connected to digital display. The memory is refreshed and restored after a certain time which can be controlled by the user.

• Intelligent Fire Detection System.

Cheap intelligent fire detection system to avoid false fire alarms. It detects smoke, high temperature and high slope in temperature rise to confirm fire. In case of smokeless fire, it relies on high temperature and high rate of increase in temperature to confirm the fire.

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• 4-bit Arithmetic and Logic Unit (ALU).

Design of 4-bit Arithmetic and Logic Unit (ALU) which will contain minimum possible number of logic gates and breadboard implementation of the ALU using basic logic gates (AND, OR, NOT, XOR). The ALU is able to do 6 operations: A+B+1, A-B, A+1, A, A XOR B, and A AND B.

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Click here to download the project files.

• 8-bit serial microprocessor (SAPI Architecture).

Conceptual design of a 8-bit serial microprocessor of common bus architecture with basic circuit elements and digital logic ICs was done and it was implemented in a digital circuit simulator called Circuit Maker. The microprocessor has 256byte memory, can take 16 different assembly instructions, and runs on 1MHz clock speed. The microprocessor consists of:

1) An input port which takes a HEX keypad.

2) Two 8-bit registers (A & B), one temporary 8-bit register, and one 4-bit flag register.

3) One 8-bit memory address register (MAR), and one 8-bit instruction register (IR).

4) 8-bit Program Counter, and 8-bit Stack Pointer (SP).

5) 256 byte RAM.

6) Arithmetic and Logic Unit (ALU), able to do addition, subtraction, increment and XOR.

7) Control Unit generating 8-bit control code each clock cycle.

8) Output Port, which will be connected to a HEX display.

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Software development:

• Fault current calculation of power systems.

I developed a program which calculates the fault current and other fault parameters of a large power system. The software takes the number of bus in the network, information of each bus, machines added to or between any two bus. Then an efficient algorithm generates the bus impedance matrix from which the fault parameters are calculated. The software was developed using Microsoft Visual Basic 6.0.

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