Akustisk trapping i system med glaskapillär - Systemoptimering och sambandet mellan resonans och trappingkraft

Sammanfattning: An engineer always strive to help in the continuous exploration of the unknown. By doing so we go further out in space and further down in scale. This is the case with microfluidics which in the last years have gotten a lot of attention. This thesis will examine and better try to understand and optimize a fluidic system that uses ultrasonic trapping. Its application may be everything from enriching a biological sample to increase the speed of forensics. The best part is that it does not hurt the cell that is trapped. This thesis will test the systems different parameters and also try to find an easy way to find the optimal trapping frequency. To do this an automated test system was built to be able to use different flows to tests the trapping force in the system. This system was also built to be able to automatically iterate the different test since they are time consuming to do manually. A big part of this thesis is to analyze the impedance of the ultrasonic transducers, this was done with an impedance- and phase analyzer. The tests show that the resonance frequency of the system correlated with the frequency that displayed the best trapping. This was shown to be a reliable hypothesis that was used to evaluate the system. It was also shown that the amount of trapped particles did correlate with the resonance frequency. With all of these results a program called ”OptiTrap” was built in order to automate the finding of the optimal trapping frequency for the system in question. The program worked and improvements where made so it can detect a trapped particle cluster. In conclusion, it was possible to find the optimal trapping frequency in an easy way. With the automated optimizing program the trapping system will get easier to evaluate and use.