| Image-charge detection is an analytical technique in which a highly-charged particle is detected by the magnitude of the image current that it generates in a detecting electrode. This current is represented as a voltage between the charged particle and the sensing electrode. It is a single particle detection method, ideal for the analysis of large, variable mass particles such as biological cells.;Some of the physical properties of Bacillus subtilis spores were explored using different applications of image-charge detection. B. subtilis is a gram-negative spore-forming bacteria that has been shown to exhibit extremophile behavior. The particular extremophile behavior that was investigated in this study is the resistance to extreme mechanical stress.;The effects of high-velocity impacts upon these spores were studied using image-charge detection. The elastic properties of these spores as well as spore survivability to high-velocity impacts were investigated. Spores were shown to survive impacts at velocities up to 299 +/- 28 m/s. The average kinetic energy loss experienced by impacting spores, regardless of velocity at impact, was between 71 and 72%. Both conventional and novel image-charge detection techniques were used for these studies.;The novel version of a charge detector that was demonstrated was fabricated using patterned metal electrodes on printed circuit boards. The simplicity and versatility of this method was demonstrated with a multi-stage charge detector, a unique bouncing detector, and charge-detection mass spectrometry detector which is capable of measuring the absolute mass of a single highly-charged particle. |
