Design and implementation of A MEMS based gravimetric detector for cytometry applications

Bayraktar, Ekrem
This thesis reports design and implementation of a MEMS based gravimetric resonator for cytometry applications. There are mainly two objectives of this thesis; to enable in-flow analysis and to perform closed loop operation that does not require any additional processing or equipment. A novel MEMS based resonator with in-flow capabilities is proposed for detection of agents inside micro channels. High resolution of mass detection inside micro channels is planned to be succeeded with lateral motion in the micro channel floor. The idea embedding lateral resonators emerges from decreasing squeeze film damping during the motion of the resonator. Lateral motion is supported by hydrophobic parylene coating to decrease the damping. Theory and design of the gravimetric resonators are explained and the fabrication flow is constructed and performed successfully by combining SOI, SOG and polymer micro fabrication techniques. Problems during the fabrication are overcome and optimized flow is presented. The devices have a foot print area of 1.5 x 0.5 cm2 which is mainly composed of reservoirs for fluidic connections. Ten types of devices are designed according to their mass sensitivities and compliances. Trade offs between frequency, injected current, and compliance are analyzed successfully by taking also the performance parameters of the interface electronics in to account. Test results reveal that single latex bead with 3 µm diameter and 14.127 pg mass can be sensed successfully and mass sensitivity is measured to be 5.91 fg/Hz for this type of device.
Citation Formats
E. Bayraktar, “Design and implementation of A MEMS based gravimetric detector for cytometry applications,” M.S. - Master of Science, Middle East Technical University, 2010.