Date of Award
Master of Science (MS)
Electrical and Computer Engineering
Chung Hoon Lee
Susan C. Schneider
Fabien J. Josse
This thesis presents a micromachined differential scanning calorimeter (DSC) for cellular differentiation and metabolism monitoring. The misregulation of cell physiology due to disease increases the metabolic rate of the cell and therefore its heat output. Observing or monitoring the cell's heat output will lead to a method to detect diseased cells and distinguish them from normal cells.
The calorimetric chambers of the DSC were fabricated on a silicon nitride thin film, which allows for rapid thermal equilibrium and insulation. The temperature sensing element was a resistive temperature detector fabricated from nickel. The DSC incorporated integrated nickel resistive heaters to apply on chip heating and for calibration.
The cell metabolism experiments carried out with the DSC were performed using JM-1 liver cancer cells and white blood cells (lymphocytes). Step voltage inputs were applied to the DSC while the response of the RTD to temperature was monitored. The results from initial testing showed a detectable increase in chamber temperature of 0.375ºC for the JM-1 liver cells. Further analysis was completed by obtaining the derivative of the DSC temperature curves. Two methods were explored: the direct derivative of the raw data curve and the derivative of the differential data curve. While both methods showed the ability to differentiate between the JM-1 liver cells and the lymphocytes, the derivative of the differential data curve was superior due to the elimination of common mode signals. The differential method also allowed the determination of the heat rates of the cells. JM-1 liver cells showed a positive heat rate which is consistent with its increased metabolism, while the lymphocytes showed a negative heat rate or absorption of thermal energy.