SUBMICRON SENSOR POSITIONING WITH REPEATABILITY AND STABILITY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Computer controlled submicron positioning will enable us to investigate methods of non-contact cell membrane detection for use as a position regulator. To this end we intend to explore the use of piezo tube positioners in addition to our linear stepper motor approach. To drive a piezo tube in 3 axes, 5 bipolar voltage sources are needed. The pulse width modulators from a PIC16f73 are used to construct a pair of boost converters capable of producing up to ¿500 Volts. The PIC monitors the voltage through an on-chip analog to digital converter and adjusts the duty cycle on its pulse width monitor to achieve the voltage requested by the host computer. For ultra fine control, analog inputs may be used to set the voltage through a pair of transistors. In this mode the PIC will set the boost converters potential 2 volts above the requested value to reduce heating. A fine position property has been added to allow the positioner to work smoothly with the existing BRC micro-manipulator.