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<P ALIGN=RIGHT><FONT COLOR="#ffffff"><FONT FACE="Verdana"><FONT SIZE=2><B><FONT SIZE=4>Frequently Asked
Questions </FONT></B></FONT></FONT></FONT> </P>
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<P><B><FONT SIZE=2><FONT FACE="Verdana">General</FONT></FONT></B> </P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.1. What are the
differences between M, CD and FD designs of IMEs?</B> </FONT></FONT> </P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The M or monolithic design
is a single pair of electrodes that are interdigitated. The CD or
combined differential is a dual design, or two pairs of
interdigitated electrodes. However, in the CD design, the two
pairs share a common central electrode that has fingers in two
directions; towards the other electrodes and thus serves as an
exposed gate electrode. The FD or full differential design
comprises two completely separate pairs of electrodes and thus
has four leads and may be thought of as two discrete M designs on
a single chip. </FONT></FONT> </P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.2. Why does ABTECH
offer these different designs?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The M, CD and FD designs
afford you flexibility in the way the IMEs are used. M for simple
materials characterizations, CD for field-gated phenomena and FD
for ratiometric analytical measurements.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.3. How is the M device
design used?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The M design may be used as
a simple, two-electrode (anode and cathode) electrochemical cell
(electrolysis) or in the measurement of resistance (DC
resistivity or conductivity) or electrical impedance (AC
impedance) of films placed on or between the digits of the
device.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.4. How is the CD device
design used?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The CD design allows a
polymer film to be cast, grown or deposited over all three
electrodes and then have the outer two electrodes be used much
like an M device (DC or AC). However, an additional potential may
be applied to the central electrode to potentiate the properties,
and hence response, of the polymer film. The electrical behavior
of the polymer film could thus be altered by the electric field
applied to the central gating electrode. This arrangement
requires a bi-potentiostat or other measurement configuration.
The gated electrode may also be “buried” by an
insulating layer.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.5. How is the FD device
design used?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The FD device can be thought
of as two separate M designs on a single chip. This allows the
possibility of a ratiometric measurement, that is, the response
of one region of interdigitation relative to the other. The FD
device may also be prepared with two entirely different polymer
films or biological molecules (enzymes, DNA, etc) on each of the
two regions of interdigitation. In this way the FD might be used
to measure two distinct analytes in the same test medium.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.6. Why does ABTECH
offer these devices with different conductors?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>ABTECH’s IME, IAME and
IAIME are available in three different conductors gold (Au),
platinum (Pt) and ITO. These conductors, while generally inert,
each have different work functions, different surface energies,
different surface chemistries, and different bio-contact
properties. This gives then unique properties. Au for example is
readily modified with alkane thiols, ITO is readily modified with
organosilanes, and Pt is easily platinized to be rendered
catalytic.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.7. What is the
difference between packaged (P) and unpackaged (U) devices?</B></FONT></FONT></P>
<P><FONT SIZE=2><FONT FACE="Verdana">ABTECH’s IMEs are
available as packaged and unpackaged devices. Unpackaged (U)
devices are microlithographically fabricated chips possessing
patterns of conductors on an insulating substrate. The unpackaged
device is supplied as a die without lead wires and without any
form of encapsulation. The packaged (P) device is provided with a
suitable chip carrier / leadwire construct and the points of
attachment of the bonding pads of the chip to the chip carrier is
encapsulated in suitable (usually epoxy) resin.
<A HREF="http://www.abtechsci.com/imep-animated.html">http://www.abtechsci.com/imep-animated.html</A></FONT></FONT></P>
<P STYLE="font-style: normal"><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.8.
Why do packaged IMEs require a two–week lead-time?</B></FONT></FONT></P>
<P STYLE="font-weight: medium"><FONT FACE="Verdana"><FONT SIZE=2>Packaged
items require a two-week lead time as chips are taken out of
inventory in response to a customer's order and are then packaged
accordingly. Because packaging (encapsulation with a suitable
epoxy resin) limits user flexibility with regard to coating
methods, ABTECH prepares packaged chips only in response to
confirmed purchase orders or receipt of credit cards. Packaged
items are thus not kept in inventory and must thus be prepared in
response to a confirmed purchase.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.9. What is a STC Test
Clip and how is it used?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The STC test clip is the
correct connector for all IME chips. The STC is a spring-loaded
pinch clip that allows easy and convenient make/break electrical
connection to the bonding pads of the various IME dies. The STC
possess four leads that terminate in four spring-loaded gold
contacts within the jaw of the STC Test Clip. The electrical
contacts of the test clip match and mate to the bonding pads of
the die. To use the test clip, its jaws are opened and the die is
inserted such that the conductive bonding pads of the die mate
with the conductors of the test clip upon its closure. Check for
connectivity using a multimeter.</FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2><B>Q.10. We are interested
in buying IAME chips and adapters. We wish to use these chips for
measuring the electrical activities of cells. We wonder if it is
at all possible to do this using your IAME chips and, if so,
whether someone has done it before. Also, what instrumentation
does one need to perform measurements?</B></FONT></FONT></P>
<P><FONT FACE="Verdana"><FONT SIZE=2>The IAME and the IAIME chips
may both be used for measuring the electrical impedance
characteristics of living cells. The cells must first be cultured
to full confluence on the chip, they must also adhere to the chip
and an impedance analyzer or lock-in amplifier could be used to
obtain the real and imaginary components of the impedance of the
cells as a function of time. To achieve cell growth on the chip a
culture chamber must be installed over the electrode fingers of
the chip. Moreover, chemistries appropriate for the
immobilization of the cells (ECM proteins of amino acid
sequences) must first be immobilized to the chip.</FONT></FONT></P>
<P><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.11. Is the
IAME wand adapter a one-time use adapter or can it be reused for
connection to multiple IAMEs?</B></FONT></FONT></P>
<P STYLE="margin-top: 0.17in"><FONT SIZE=2><FONT FACE="Verdana, sans-serif">While
it is possible to use one wand with multiple </FONT></FONT><A HREF="http://www.abtechsci.com/imep-animated.html"><FONT SIZE=2><FONT FACE="Verdana, sans-serif">IAME
chips</FONT></FONT></A> <FONT SIZE=2><FONT FACE="Verdana, sans-serif">or
IME Chips, they were designed to be used as one wand per chip.
The chip is typically glued (Crazy Glue® - cyanoacrylate) to
the wand and then the electrical contacts established using a
conductive epoxy or low temperature solder. To use a single wand
and multiple chips will require that you invent a method of
attachment and detachment (other than gluing) and a method for
making and breaking (other than conductive epoxy) the electrical
contacts from wand to chip. <B>It is therefore advised that you
purchase as many wands as you purchase chips. </B>Please take a
look at this animation of IAME chip packaging.
</FONT></FONT><A HREF="http://www.abtechsci.com/imep-animated.html"><FONT SIZE=2><FONT FACE="Verdana, sans-serif">http://www.abtechsci.com/imep-animated.html</FONT></FONT></A></P>
<P><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.12</B><B>.
To what temperature can I heat my IME/IAME/IAIME/MDEA Chip?</B></FONT></FONT></P>
<P><FONT SIZE=2><FONT FACE="Verdana, sans-serif">Our chips are fabricated from Schott D263 borosilicate glass and possess an appropriately patterned conductor. These devices are manufactured for RT use and are suitable for modest variations above and below RT. However, it is possible to use these devices at elevated temperatures as well as at cryogenic temperatures. The glass transition temperature, Tg, or softening point for Schott D263 is given by Schott as 557oC. Above this temperature the substrate looses its dimensional stability.</FONT></FONT></P>
<P><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.1</B>3<B>.
I have purchased an IAME / IME Chip and IAME / IME Wand Adapter.
How do I make connection of the wand to the chip?</B> </FONT></FONT> </P>
<P><FONT SIZE=2><FONT FACE="Verdana, sans-serif">We recommend,
without guarantee, the use of a conductive two-part epoxy such as
that from Circuit Works CW2400 Part A and CW2400 Part B
</FONT></FONT><A HREF="http://www.chemtronics.com/"><FONT SIZE=2><FONT FACE="Verdana, sans-serif">www.Chemtronics.com</FONT></FONT></A><FONT SIZE=2><FONT FACE="Verdana, sans-serif">.
Also, you may solder the connection if you have access to a
temperature controlled solder station.</FONT></FONT></P>
<P><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.1</B>4<B>.
I have purchased IMEs and wish to measure conductivity of a well-studied material so that I may obtain cell constants and calibrate the electrode.
What is a suitable material to use</B></FONT></FONT><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>?</B> </FONT></FONT> </P>
<P><FONT SIZE=2><FONT FACE="Verdana, sans-serif">We recommend,
without guarantee, the use of standard conductance solutions of potassium chloride (KCl) at constant temperature (25C) according to <a href="http://www.iso.org/iso/catalogue_detail.htm?csnumber=14838">ISO 7888:1985</a>. Such solutions are commercially available from VWR, Fischer Scientific, Sigma Aldrich, etc. and vary in conductance values from 0.147 to 12.90 mS/cm. <span class="style1">See Y. C. Wu and P. A. Berezansky, "Low Electrolytic Conductivity Standards"<a href="http://nvl.nist.gov/pub/nistpubs/jres/100/5/j15wu.pdf"> <em>J. Res. Natl. Inst. Stand. Technol.</em></a> (<strong>1995</strong>) 100, 521 and Liju Yang, Adilah Guiseppi-Wilson and Anthony Guiseppi-Elie "Design considerations in the use of interdigitated microsensor electrode arrays (IMEs) for impedimetric characterization of biomimetic hydrogels"</span> <a href="http://www.springerlink.com/content/305371556vqj3630/" title="Link to the Journal of this Article" lang="en"><em>Biomedical Microdevices</em></a> (<strong>2010</strong>) DOI: 10.1007/s10544-010-9492-4.</FONT></FONT></P>
<P><FONT FACE="Verdana, sans-serif"><FONT SIZE=2><B>Q.1</B>5<B>.
I have purchased IAME / IME / PME / MDEA or other chip and wish to know, for my thesis or publication, know exactly how these devices are manufactured?</B> </FONT></FONT> </P>
<P><FONT SIZE=2><FONT FACE="Verdana, sans-serif">The exact process details of manufacture (pressures, times, temperatures, etc.) are proprietary. However, the general technical description of the manufacture of these chips have been published and may be found in such peer-reviewed journal articles as</FONT></FONT></P>
<ul>
<li>Liju Yang, Adilah Guiseppi-Wilson and Anthony Guiseppi-Elie "Design considerations in the use of interdigitated microsensor electrode arrays (IMEs) for impedimetric characterization of biomimetic hydrogels" <a href="http://www.springerlink.com/content/305371556vqj3630/" title="Link to the Journal of this Article" lang="en"><em>Biomedical Microdevices</em></a> (<strong>2010</strong>) DOI: 10.1007/s10544-010-9492-4.</li>
<li><strong>Anthony Guiseppi-Elie</strong>, Abdur Rub Abdur Rahman and Nikhil K. Shukla “SAM-modified Microdisc Electrode Arrays (MDEAs) With Functionalized Carbon Nanotubes” <em>Elctrochimica Acta</em> <strong>(2010)</strong> 55(14), 4247-4255<strong> </strong><img width="1" height="10" src="faqs_clip_image002.gif"><a href="http://dx.doi.org/10.1016/j.electacta.2008.12.043" target="doilink">doi:10.1016/j.electacta.2008.12.043</a></li>
<li>Abdur Rub Abdur Rahman, Gusphyl Justin, Adilah Guiseppi-Wilson and Anthony Guiseppi-Elie* “Fabrication and Packaging of a Dual Sensing Electrochemical Biotransducer for Glucose and Lactate Useful in Intramuscular Physiologic Status Monitoring” <em>IEEE Sensors Journal</em> (<strong>2009</strong>) 9(12): 1856-1863 <a href="http://dx.doi.org/10.1109/JSEN.2009.2031347">doi: 10.1109/JSEN.2009.2031347</a> (IF=1.17)</li>
<li>Abdur Rub Abdur Rahman and <strong>Anthony Guiseppi-Elie</strong> “Design Considerations in the Development and Application of Microdisc Electrode Arrays (MDEAs) for Implantable Biosensors” <em>Biomedical Microdevices: BioMEMS and Biomedical NanoTechnology</em> <strong>(2009) </strong>11:701-710. <a href="http://www.doi.org/10.1007/s10544-008-9283-3">http://www.doi.org/10.1007/s10544-008-9283-3</a> (IF=2.92) </li>
</ul> <P>s</P></TD>
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Scientific, Inc.<BR>
800 East Leigh Street, Richmond,
Virginia 23219<BR>
Telephone Number: +1-804-783-7829 Fax Number:
+1-804-783-7830<BR>e-mail: <A HREF="mailto:[email protected]">[email protected]</A></FONT></FONT></P>
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