1. CNT as Thermal Resistive Sensor Yu ZHANG Directed by Prof. Wen J. LI April 30, 2010

2. Measurement Noise References 1.Steven W. Smith, The Scientist and Engineer's Guide to Digital Signal Processing, Chapter 25The Scientist and Engineer's Guide to Digital Signal Processing 2.http://en.wikipedia.org/wiki/Audio_system_measurementshttp://en.wikipedia.org/wiki/Audio_system_measurements 3.J. Silva etc, Systematic characterisation of silicon-embedded accelerometers for mechanomyography, in Journal of Medical and Biological Engineering and Computing, 2006Medical and Biological Engineering and Computing 4.T. Kajita etc, A Two-Chip Interface for a MEMS Accelerometer, in IEEE Transactions on Instrumentation and Measurement, Vol. 51, NO. 4, pp853-858, AUGUST 2002 5.Analog Devices Datasheet of ADMP404 Omnidirectional Microphone with Bottom Port and Analog Output, 2010Datasheet 6.Z. Fan etc., Signal descriptions and formulations for long range UHF RFID readers, in Progress In Electromagnetics Research, PIER 71, 109–127, 2007 WIFI: Excellent signal WIFI: No signal WIFI: Lowsignal Cassette Player 2 80dB - 10dB - 20dB - 30dB - 40dB - 50dB - 60dB - 70dB - 90dB - 100dB - CD Player 2 MEMS Accelerometer 3 (Maximum Value) MEMS Accelerometer 4 (Maximum Value) MEMS microphone 5 Analog Devices ADMP404 RFID Reader 6 CCD Camera 1 Improving sampling accuracy of the SMU SNR upper limit of the SMU Weakened signal due to small Resistance Increased noise due to over-heating

3. Origin of Research A conductive thermal flux density to substrate and electrodes thermal flux density to the air caused by convection 1 References 1.M. Elwenspoek and R. Wiegerink, Mechanical Microsensors, 2001 How to explain the relationship between current and response? CNT is more sensitive to temperature change at low current

4. Temperature Coefficient of Resistance R 0 is the sensor’s resistance at T 0 R is the sensors resistance at T Ambient temperatureCNT temperature Testing current = 10uA

5. Measurement-induced Joule Heating  Any electrical tests will introduce measuring current to the Device Under Test (DUT)  Nano/Micro structures have very low heat capacitance  Test-induced current will heat up the nano DUT To what level?

6. Resistance vs Current The declination of the R/I curve indicates: R CNT drops significantly when testing current augments from1nA to 100nA Higher testing current means higher CNT temperature T ( ℃ ) ΔR ～ 10kΩ ΔT=60 ℃ ΔR ～ 70kΩ ΔT=? ℃ Unable to determine the temperature increment 1nA to 10uA sweep tests at T amb from 20 ℃ to 80 ℃ with 5 ℃ steps

7. Conclusion on TCR Test The Joule Heating phenomena of the CNT bundle occurs from nA level (or even smaller) – Unable to obtain R 0 and T 0 unless – The calculated TCR at different testing current cannot be used to judge the thermal resistive properties of CNTs

8. Proposed Future Work Explain the Response-Current curve through other approaches Test and compare the R-I curve of different configurations