Biomedical Engineering Reference
In-Depth Information
changes and function. Unlike patch-clamp techniques, such methods can offer
continuous measurements while the cells are stimulated, without destroying the
cells in the process. Observations can be made after the stimulus is removed, on
a still living cell. Bioelectronic devices based on fields of variable frequency can
measure cellular activity and interaction with drugs, leading to spectacular
applications ranging from nanomedicine to repair and regeneration tech-
nologies. Today, classical microscopy (optical, electron microscopy), which
shows only the physical aspect of the cell, is plagued by detection limits. It can
be complemented by high-resolution, extremely sensitive methods translating
the spatial and temporal characteristics of living systems into the frequencies
and amplitudes of a complex transducing signal, carrying ample and valuable
information. Such methods have the potential to open new windows in cell
biology and neuroscience in particular.
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5.2.1 The Simple Vibrating Probe
The history of the scientific development of cellular biosensors is extremely
relevant to the current state-of-the-art. In the 1970s Richard Nuccitelli
discovered that small direct current (DC) electric signals (having important
functions in processes such as embryo development, cell migration, wound
healing, etc.) can be detected around living cells using a small vibrating probe.
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The probe consisted of a metal wire 10-30 mm in diameter that was sharpened,
had a small platinum black tip and was electrically insulated. It was set in
vibration at 300Hz by a piezoelectric bender (Figure 5.1).
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Set-up of vibrating probe technique for measuring cellular currents.
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(Reprinted by kind permission of the Rockefeller University Press.)
Figure 5.1
