We are grateful to Professor Richard Borgens, Center for Paralysis Research, Purdue University, for help in assembling the vibrating probe system. This study was supported by NEI grant NIH 1R01EY019101 to MZ and BR, and in part by grants from the California Institute of Regenerative Medicine RB1-01417, NSF MCB-0951199, and by an Unrestricted Grant from Research to Prevent Blindness, UC Davis Ophthalmology.

1. Probe Manufacture
Blank probes are purchased from World Precision Instruments (elgiloy/stainless parylene-coated microelectrodes) (see 'Table of specific reagents and equipment' below). The probe is cut 25-30 mm behind the tip and about 5 mm of parylene insulation at the cut end scraped away with a scalpel (#11 blade) to ensure a good connection. The probe is mounted in a gold R30 connector using electrically-conductive silver-loaded epoxy (e.g. Rite-Lok SL65) [*see note below]. The probe i...

<ol>
	<li>Reid, B., Nuccitelli, R., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+measurement+of+bioelectric+currents+with+a+vibrating+probe.">Non-invasive measurement of bioelectric currents with a vibrating probe.</a> Nat. Protoc. 2, 661-9282 (2007).</li><li>Reid, B., Song, B., McCaig, C. D., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wound+healing+in+rat+cornea:+the+role+of+electric+currents.">Wound healing in rat cornea: the role of electric currents.</a> FASEB J. 19, 379-386 (2005).</li><li>Lois, N., Reid, B., Song, B., Zhao, M., Forrester, J. V., McCaig, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric+currents+and+lens+regeneration+in+the+rat.">Electric currents and lens regeneration in the rat.</a> Exp. Eye Res. 90, 316-323 (2010).</li><li>Wang, E., Reid, B., Lois, N., Forrester, J. V., McCaig, C. D., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+inhibition+of+lens+epithelial+cell+proliferation:+an+additional+factor+in+secondary+cataract.">Electrical inhibition of lens epithelial cell proliferation: an additional factor in secondary cataract.</a> FASEB J. 19, 842-844 (2005).</li><li>Guo, A., Song, B., Reid, B., Gu, Y., Forrester, J. V., Jahoda, C., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+physiological+electric+fields+on+migration+of+human+dermal+fibroblasts.">Effects of physiological electric fields on migration of human dermal fibroblasts.</a> J. Invest. Derm. , (2010).</li><li>Reid, B., Song, B., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric+currents+in+Xenopus+tadpole+tail+regeneration.">Electric currents in Xenopus tadpole tail regeneration.</a> Dev. Biol. 335, 198-207 (2009).</li><li>Zhao, M., Song, B., Pu, J., Wada, T., Reid, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+signals+control+wound+healing+through+phosphatidylinositol-3-OH+kinase-&#947;.">Electrical signals control wound healing through phosphatidylinositol-3-OH kinase-&#947;.</a> 442, 457-460 (2006).</li><li>Reid, B., EO, G. r. a. u. e. -. H. e. r. n. a. n. d. e. z., Mannis, M. J., Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulating+endogenous+electric+currents+in+human+corneal+wounds+-+a+novel+approach+of+bioelectric+stimulation+without+electrodes.">Modulating endogenous electric currents in human corneal wounds - a novel approach of bioelectric stimulation without electrodes.</a> Cornea. , (2010).</li><li>Nuccitelli, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ultrasensitive+vibrating+probe+for+measuring+steady+extracellular+currents.">An ultrasensitive vibrating probe for measuring steady extracellular currents.</a> J. Cell Biol. 63, 614-628 (1974).</li><li>Hotary, K. B., Nuccitelli, R., Robinson, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+computerized+2-dimensional+vibrating+probe+for+mapping+extracellular+current+patterns.">A computerized 2-dimensional vibrating probe for mapping extracellular current patterns.</a> J. Neurosci. Meth. 43, 55-67 (1992).</li><li>Nuccitelli, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endogenous+ion+currents+and+DC+electric+fields+in+multicellular+animal+tissues.">Endogenous ion currents and DC electric fields in multicellular animal tissues.</a> Bioelectromagnetics Supplement. 1, 147-157 (1992).</li><li>Levin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioelectric+mechanisms+in+regeneration:+Unique+aspects+and+future+perspectives.">Bioelectric mechanisms in regeneration: Unique aspects and future perspectives.</a> Seminars in Cell Dev. Biol. 20, 543-556 (2009).</li><li>Zhao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric+fields+in+wound+healing+-+An+overriding+signal+that+directs+cell+migration.">Electric fields in wound healing - An overriding signal that directs cell migration.</a> Seminars in Cell Dev. Biol. 20, 674-682 (2009).</li></ol>

We describe a low cost, basic, but highly sensitive vibrating probe system for measuring non-invasively electric current in a variety of biological systems.
Possible Modifications
<ol>
	<li>If platinum/iridium electrodes (World Precision Instruments; cat # PTM23B20) are used instead of stainless steel, then the gold plating stage can be eliminated.</li>
</ol>
Applications
We have used the vibrating probe to measure electric current in: ra...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Eligoy-Stainless Electrode</td>
<td>&nbsp;</td>
<td>World Precision Instruments</td>
<td>SSM33A70</td>
<td>76 mm, 7 M&Omega;, 1-2&mu;m tip</td>
</tr>
<tr>
<td>Gold R30 connector</td>
<td>&nbsp;</td>
<td>www.vectorelect.com</td>
<td>R30</td>
<td>Re-usable</td>
</tr>
<tr>
<td>Silver-loaded epoxy</td>
<td>&nbsp;</td>
<td>3M</td>
<td>SL65</td>
<td>Mix 1-part Resin with 1-part Hardener</td>
</tr>
<tr>
<td>Dissecting microscope</td>
<td>&nbsp;</td>
<td>Olympus</td>
<td>SZ40</td>
<td>Magnification x6 to x40</td>
</tr>
<tr>
<td>Potassium dicyanoaurate (KAu(CN)2)</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>379867</td>
<td>CAUTION: Toxic</td>
</tr>
<tr>
<td>Chloroplatinic acid hydrate (H2PtCl6 x 6H2O)</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>520896</td>
<td>CAUTION: Toxic</td>
</tr>
<tr>
<td>Lead(II) acetate trihydrate (Pb(CH3CO2)2 x 3H2O)</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>185191</td>
<td>CAUTION: Toxic</td>
</tr>
<tr>
<td>Nano-Amp power source</td>
<td>&nbsp;</td>
<td>Made in-house</td>
<td>-</td>
<td>Powered by six 1.5 V (AAA) batteries</td>
</tr>
<tr>
<td>3-dimensional micro-positioner</td>
<td>&nbsp;</td>
<td>Line Tool Co.</td>
<td>Model H</td>
<td>&nbsp;</td>
<tr>
<td>Lock-in amplifier</td>
<td>&nbsp;</td>
<td>Stanford Research Systems</td>
<td>SR530</td>
<td>&nbsp;</td>
<tr>
<td>Digital I/O interface</td>
<td>&nbsp;</td>
<td>National instruments</td>
<td>PCI-6220</td>
<td>&nbsp;</td>
<tr>
<td>Shielded Connector Block with BNC connections</td>
<td>&nbsp;</td>
<td>National instruments</td>
<td>BNC-2110</td>
<td>&nbsp;</td>
<tr>
<td>Strathclyde Electrophysiology Software</td>
<td>&nbsp;</td>
<td>University of Strathclyde Institute of Pharmacy and Biomedical Sciences, UK</td>
<td>WinWCP V4.1.5</td>
<td>Free download from: <a href="http://spider.science.strath.ac.uk/sipbs/software_ses.htm">http://spider.science.strath.ac.uk/sipbs/software_ses.htm</a></td>
</tr>
<tr>
<td>Calibration Chamber</td>
<td>&nbsp;</td>
<td>Made in-house</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Constant Current Calibrator</td>
<td>&nbsp;</td>
<td>Vibrating Probe Company</td>
<td>&nbsp;</td>
<td>Powered by one 9 V (PP3) battery</td>
</tr>		</tbody>
		</table>
		</div>

measurement of bioelectric current with a vibrating probe

Electric fields, generated by active transport of ions, are present in many biological systems and often serve important functions in tissues and organs. For example, they play an important role in directing cell migration during wound healing. Here we describe the manufacture and use of ultrasensitive vibrating probes for measuring extracellular electric currents. The probe is an insulated, sharpened metal wire with a small platinum-black tip (30-35 &mu;m), which can detect ionic currents in the &mu;A/cm2 range in physiological saline. The probe is vibrated at about 200 Hz by a piezoelectric bender. In the presence of an ionic current, the probe detects a voltage difference between the extremes of its movement. A lock-in amplifier filters out extraneous noise by locking on to the probe's frequency of vibration. Data are recorded onto computer. The probe is calibrated at the start and end of experiments in appropriate saline, using a chamber which applies a current of exactly 1.5 &mu;A/cm2. We describe how to make the probes, set up the system and calibrate. We also demonstrate the technique of cornea measurement, and show some representative results from different specimens (cornea, skin, brain).

Watch this Scientific Journal Video about Measurement of Bioelectric Current with a Vibrating Probe at JoVE.com

Measurement of Bioelectric Current with a Vibrating Probe

The manufacture, calibration and use of non-invasive vibrating probes to measure bioelectric current in various biological systems is described.

Electric fields, generated by active transport of ions, are present in many biological systems and often serve important functions in tissues and organs. ...

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14.0K visualizações.  University of California, Davis. A fabricação, calibração e uso de sondas não-invasivo para medir a corrente de vibração bioelétrica em diversos sistemas biológicos é descrito.