Department of Electrical and Computer Engineering SDP team Yngvesson Ioan Tihenea Tomas Broka Dmitriy Stupak Sergey Derivolkov IR CARBON NANO- TUBE TRANCEIVER

Department of Electrical and Computer Engineering

SDP team Yngvesson

Ioan TiheneaTomas Broka

Dmitriy StupakSergey Derivolkov

IR CARBON NANO-TUBE TRANCEIVER


Recap Design Overview

For our Senior Design Project we are attempting to create a communication channel which, at its core, will transmit a beam of IR radiation through a pair of lenses to be detected by an Single-Walled Carbon Nanotube (SWNT) Thin Film.

On the transmitter end, a computer will transmit binary code to a microcontroller which will create impulses to the IR LED. The IR beam will be detected by the SWNT thin film and a microcontroller on the back end will convert the impulses back to binary code to be displayed on a second computer.


System Diagram


Progress on the Computer Interface

We have developed a basic user interface in Java.

We have also successfully communicated back and forth through the USB cable to the microcontroller using sample and test programs that come with the microcontroller software development kit.


Progress on the Signal Processing

We have the circuitry on both ends assembled on the prototype boards and tested.

Learned the microcontroller architecture. The model of the microcontroller is C8051F340 from SI Labs,

Transmitter Side Receiver Side


Progress on the Transceiver

We have slowly improved our device making techniques to create better quality and more robust suspended films.

We have purchased two 10mm lenses that work well within the IR range we need.

We fabricated multiple acceptable quality retainers to house and suspended the SWNT films.

Test data has given us evidence that IR light has effected the resistivity of the SWNT thin film when shined upon.


Process of Making a Suspended SWNT Thin Film


Pictures and Samples


Statistics

R(ohm) V_o(V) V_ir(V) deltaV(mV)8.2k 6.1430 6.1440 1.00

10k 5.5200 5.5220 2.0012k 4.8904 4.8841 6.3015k 4.1358 4.1388 3.0018k 3.6078 3.6126 4.8025k 2.7753 2.7776 2.3030k 2.3830 2.3845 1.5047k 1.6000 1.6013 1.30


Work Still to be Done

We need to develop the assembly code for the microcontroller to read a received text file from the memory and transfer it with controlled impulses to the IR LED on the front end of the system. The back end will be similar but it will receive impulses and save them into the memory.

We need to fine-tune the film making process to develop satisfactory quality film which will better respond to the IR radiation shined onto it.

Define I-V characteristics for the suspended film. Construct retainers for lenses. Amplify train of pulses detected by the SWNT thin film.


Obstacles

One major obstacle is creating a robust film that is precisely suspended. The films that we have are very fragile and tend to break during the acetone bath treatment. Because of this fragility, it is difficult to wash the dissolvable membrane without breaking the film.

One possible solution is to create thicker films which is what we have been doing. Also we have become more experienced with the handling of the film.

Another big obstacle is in the amplification process. The voltage changes from the SWNT thin film are at the present very small and a very sensitive amplifier is needed. However, with a sensitive amplifier, there is a great deal of noise that gets amplified so that the change in the film voltage is presently undetectable.


Goal for FPR and Demo Day

Our goals for FPR and Demo day are

To be able to demonstrate that the SWNT Thin Film detector works.To send a train of impulses through the system representing binary code.Given a good quality suspended film, to demonstrate the speed of the SWNT Thin Film detector.


Questions

We will now take questions at this time.


Transmitter PCB Layout


Documents

Department of Electrical and Computer Engineering SDP team Yngvesson Ioan Tihenea Tomas Broka Dmitriy Stupak Sergey Derivolkov IR CARBON NANO- TUBE TRANCEIVER