Radio-frequency microtools for particle and live cell manipulation

Abstract

Single particles can be manipulated by applying high frequencies to ultramicro electrode arrays fabricated on planar structures. Heat production can be reduced to the extent that intense electric fields can be applied even to unmodified cell culture media. Animal cells grow normally in the high field (up to 100 kV/m) between such continuously energized multielectrodes. As with laser tweezers [1-3], this technique can capture particles and cells in field traps, generate linear movement, and permit cell cultivation. It can also produce micropatterns of pH gradients, field-cast objects, and control cell adhesion. These microtools may be combined to develop cell separators, microsensors, and controlled-biocompatibility surfaces.

Role of peroxide in AC electrical field exposure effects on Friend murine erythroleukemia cells during dielectrophoretic manipulations

“…Heat is often produced during field exposure by Joule heating and by dielectric losses, and electrolysis may also occur at low frequencies [15]. Fuhr and others [15,41] showed that exposure of 3T3 and L929 fibroblast cells to a high frequency field (1-40 MHz) extended cell cycle time moderately (from 18 h to 26 h for the 3T3 fibroblast cells, for example), but did not significantly change their viability, motility, anchorage properties. However, a comprehensive study of AC field exposure effects on cells for sub-MHz frequencies, which is the most important range for DEP manipulations (see below), is not known to the authors.…”

“…Useful and effcient DEP discrimination and separation of mammalian cells occur close to their DEP cross-over frequency (where Re(f CM )~0), as well as in the frequency range where Im(f CM ) is a maximum [22,23]. For mammalian cells suspended in a typical electromanipulation medium (conductivity around 50 mS/m or less), the frequency region of interest is in the range 1 kHz-1 MHz [15,22,23]. In this paper, the effects of the AC field exposure of DS19 Friend murine erythroleukemia cells in the frequency range 100 Hz-10 MHz are reported.…”

“…Although far less work has been reported for AC field exposure of cells, it is suspected that many membrane enzymes may absorb and transduce energy from the oscillating field [28], and it has been shown that cells exposed to an alternating field for a period of time can become more resistant to field pulses of high intensity and long duration (field stability) [28]. Heat is often produced during field exposure by Joule heating and by dielectric losses, and electrolysis may also occur at low frequencies [15]. Fuhr and others [15,41] showed that exposure of 3T3 and L929 fibroblast cells to a high frequency field (1-40 MHz) extended cell cycle time moderately (from 18 h to 26 h for the 3T3 fibroblast cells, for example), but did not significantly change their viability, motility, anchorage properties.…”

“…Alternatively, if the field is rotating, the interaction between the field and the induced dipole will make the particle rotate (ROT: electrorotation) [9][10][11]. The techniques of DEP and ROT can be used noninvasively to characterize the dielectric properties of individual biological cells and have led to new methods for cell characterization, manipulation and, particularly, cell sorting [12][13][14][15][16][17][18][19][20][21][22][23][24]. As a cell sorting method, these techniques have the advantage of being simple, easy to use and non-invasive [22,23].…”

Trapping cortical rat neurons

“…It was already stated that low frequencies (<lo0 P.O. Box 217,7500 AE Enschede kHz) [6] can cause excessive charging of the cell membrane, The Netherlands which might lead to irreversible changes of the properties of T. Heida@el …”