Baikie, I.D., Smith, P.J.S., Porterfield, D.M. and Estrup, P.J.
Multitip scanning bio-Kelvin probe
Review of Scientific Instruments, 70, (3), . (doi:10.1063/1.1149678).
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We have developed a novel multitip scanning Kelvin probe which can measure changes in biological surface potential ?Vs to within 2 mV and, quasisimultaneously monitor displacement to <1 ?m. The control and measurement subcomponents are PC based and incorporate a flexible user interface permitting software control of each individual tip, measurement, and scan parameters. We review the mode of operation and design features of the scanning bio-Kelvin probe including tip steering, signal processing, tip calibration, and novel tip tracking/dithering routines. This system uniquely offers both tip-to-sample spacing control (which is essential to avoid spurious changes in ?Vs due to variations in mean spacing) and a dithering routine to maintain tip orientation to the biological specimen, irrespective of the latter’s movement. These features permit long term (>48 h) “active” tracking of the displacement and biopotentials developed along and around a plant shoot in response to an environmental stimulus, e.g., differential illumination (phototropism) or changes in orientation (gravitropism). © 1999 American Institute of Physics.
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