FACULTY OF ENGINEERING
LAB SHEET
NANO/MICRO-ELECTROMECHANICAL SYSTEMS
(N/MEMS)
ENT4046
TRIMESTER 2 (2015/2016)
MS 1 :MEMS (Prediction)
MS 2 : MEMS (Experiment)
*Note: On-the-spot evaluation will be carried out during or at the end of the experiment
based on preparatory questions. Students are advised to read through this lab sheet
before doing experiment. Your performance, teamwork effort, and learning attitude will
count towards the marks.
MEMS:
Microchip
electrophoresis
conductivity detection
withcapacitively-coupled
contactless
Objectives
After completing the two laboratory phases on microchip electrophoresis (MCE) with capacitivelycoupled contactless conductivity detection (C4D):
MS 1 : MEMS (Prediction)
MS 2 : MEMS (Experiment)
the students will be able
(1) To understand the operation principle of microchip electrophoresis, a microfluidic-based
MEMS application.
(2) To perform experimental studies and analysis with contactless conductivity measurement
in electrophoresis process.
Introduction
Microfluidic is a distinct part of MEMS that utilized the laminar flow of fluid in micro-scaled
channels or capillaries. In contrast of the chaotic and unpredictable nature of turbulent
flow, position of a particle in the fluid stream as a function of time can be determined in
laminar flow by taking into account the diffusion process and the effects of external
forces. One of the applications based on laminar flow in microfluidic devices is microchip
electrophoresis, where the process of electrophoresis is performed on a single chipfor
injection, separation, transportation and characterization. The configuration has the
advantagesof being smaller in sample volume, minimal use of reagent, higher in applied
field, higher velocities and thus faster to produce results.
Electrophoresis is the process where the motion of a charged (ions) caused by a
non‐uniform electricfield. Figure 1 show an example of capillary electrophoresis. The
velocity of an ion of charge, in a homogeneous medium, is proportional to the applied
electric field.Therefore, ions will move at characteristic velocities determined by their
charges, radii, and mobilities.
Figure 1 Capillary Electrophoresis with optical detection.
When an electric field E is applied to a spherical particle of charge Zeand radius a in a
stationary liquid of low electrical conductivity, say de-ionized water, particle movement is
influenced by the applied electric field. The low conductivity of the liquid implies the lack
of ions that otherwise would have accumulated around the charged particle and partly
neutralized its charge (electrical screening). Figure 2 show the forces that are acting on
the charged particle.
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Figure 2.Electrophoresis.A spherical particle of charge Zeand radius a moves in
a low-conductivity liquid with viscosity under the infuence of an applied
electrical Field E. The motion becomes stationary at the velocity 𝑢𝑒𝑝 , when the
Stokes drag force 𝑭𝑑𝑟𝑎𝑔 balances the electrical driving force 𝑭𝑒𝑙 .
The electric force is simply𝑭𝑒𝑙 = 𝑍𝑒𝑬. During a short time-scale of a few µs, the charged
particle reaches steady-state motion, where the electrophoretic velocity 𝑢𝑒𝑝 , is due to
viscous drag force. In this situation the Stokes drag force 𝑭𝑑𝑟𝑎𝑔 = −6𝑎𝑢𝑒𝑝 , balances
𝑭𝑒𝑙 ,
𝑭𝑡𝑜𝑡𝑎𝑙 = 𝑭𝑒𝑙 + 𝑭𝑑𝑟𝑎𝑔 = 0
𝑢𝑒𝑝 =
wherethe proportionality constant
2
𝑍𝑒
6𝑎
𝜇𝑖𝑜𝑛 =
𝑬 = 𝜇𝑖𝑜𝑛 𝑬
𝑍𝑒
6𝑎
(1)
(2)
is called the ionic or electrophoretic
-1
mobility,(-ve for anions) (cm ·(V·s) )
𝑢𝑒𝑝 is the electrophoretic velocity or migration rate (cm·s-1),
𝑬is the electric field (V·cm-1),
is the viscosity of the medium (Pa. s)
The electrophoretic mobility is proportional to the ionic charge of a sample and inversely
proportional to any frictional forces present in the buffer. When two species in a sample
have different charges or experience different frictional forces, they will separate from
one another as they migrate through a buffer solution. The frictional forces experienced
by an analyte ion depend on viscosity of the medium and the size and shape of theion.
𝑎=
𝑘𝐵 𝑇
(3)
6D
wherekB is the Boltzmann constant, and Tis the temperature, D is the diffusion
coefficient.
The electrophoretic mobility can be determined experimentally from the migration time
and the field strength:
𝐿
𝐿
𝑡𝑟
𝑉
𝜇𝑖𝑜𝑛 = ( )( 𝑡)
(4)
where𝐿is the distance from the inlet to the detection point,𝑡𝑟 is the time required for the
analyte to reach the detection point (migration time), 𝑉 is the applied voltage (field
strength), and𝐿𝑡 is the total length of the capillary.The experimental values for some ions
are shown in Table 1. In addition, the ionic mobility is directly related to the ionic
conductivity 𝜎𝑖𝑜𝑛
𝜎𝑖𝑜𝑛 = 𝑍𝑒𝑐𝑖𝑜𝑛 𝜇𝑖𝑜𝑛
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(5)
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where𝑐𝑖𝑜𝑛 is the ionic concentration (in M). Since only charged ions are affected by the
electric field, neutral analytes are poorly separated by capillary electrophoresis. (1 mM is
100mol/m3, 1 mol contains NA or 6.02214 ×1023 atoms or molecules)
Ions at T = 25 C
H+
Ag+
K+
Li+
Na+
Br-
Cl-
F-
I-
OH-
Mobility, 𝜇𝑖𝑜𝑛
[10-8 m2 (Vs)-1]
36.2
6.42
7.62
4.01
5.19
8.09
7.91
5.7
7.96
20.6
Diffusivity D
[10-9 m2 s-1]
9.31
-
1.96
1.03
1.33
2.08
2.03
1.46
2.05
5.30
Table 1. Experimental values for ionic mobility and diffusivity for small ions in aqueous
solutions at small concentrations.
The velocity of migration of an analyte in capillary electrophoresis will also depend upon
the rate of electroosmotic flow (EOF) of the buffer solution. In a typical system, the
electro-osmotic flow is directed toward the negatively charged cathode so that the buffer
flows through the capillary from the source vial to the destination vial. Separated by
differing electrophoretic mobilities, analytes migrate toward the electrode of opposite
charge. As a result, negatively charged analytes are attracted to the positively charged
anode, counter to the EOF, while positively charged analytes are attracted to the
cathode. The velocity of the electroosmotic flow is given by𝑢𝑜 = 𝜇𝑜 𝑬.
After injection and separation, analytesin electrophoresis process can bedetected by
various methods, namelyoptical based such laser induced fluorescence or absorption,
mass spectroscopy, electrochemical detection and also contactless conductivity
detection. In the current experiment, the conductivity of the fluid is measured by
electrodes and reference electrodes configured on the microchip. The principle of
measurement can also be used in capillary electrophoresis, Ion Chromatography (IC)
and High-Performance Liquid Chromatography (HPLC) and Flow Injection Analysis
(FIA). The basis of contactless conductivity measurements is explained in Figure 3.
(a)
(b)
(c)
Fig 3 (a) C4D uses a transmitter electrode to subject a sample region to a large
amplitude, high frequency electromagnetic signal. A corresponding, attenuated, AC
signal registers at a receiver electrode. (b) The size of the received signal is affected
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by the conductivity of the sample. (c) The received AC signal is deconvoluted to
convert the amplitude into a DC analog voltage signal appropriate for data collection.
In capactively coupled contactless conductivity measurements an AC-voltage is applied
to one of the galvanicallyisolated electrodes and the resulting AC-current is measured at
the second electrode. This is possible as the electrodes formcapacitors with the
electrolyte solution which are transparent for ac-signals.
The usual axial arrangement of two tubular electrodes used on a conventional capillary is
illustrated in Fig. 4(a) along with a simplified equivalent circuit diagram given in Fig. 4(b).
The method has been widely applied in the analysis of inorganic ions, organic ions,
andbio-molecules. An example for measurement of inorganic cation in blood sample is
shown in Figure 5.
(a)
(c)
(b)
Fig. 4 (a) Schematic drawing of a C4D cell for conventionalcapillary electrophoresis. (b) Simplified equivalent circuitdiagram in presence of direct capacitive
coupling betweenthe electrodes. (c) Schematic drawing of contactless
conductivity detection formicrochip electrophoresis.
Fig. 5 Determination of inorganic cations in blood serum sample using MCEC4D . Electrolyte solution, 15mM L-arginine, 10.90mM maleic acid, 1.5mM 18crown-6 (pH 5.85). (A) Bloodserum sample (diluted 1:50), (B) blood serum
sample spiked with 1.5mM Li1 (diluted 1:50).
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MS1 Prediction
Microchip electrophoresis withC4D
Activities:
1. Identify the parameters that contribute to ions movement in solution.
2. Detection of cation and anion in test solution.
3. Find the appropriate concentration to be used in microchip electrophoresis
experiment by varying the concentration ofbackground electrolyte oranalytes
(cation and anions).
Test solution:
Background electrolytes(BGE) = 0.5M acetic acid
Sample = 1mMLiCl, KNO3, Na2SO4in deionised water
Micronit microfluidic chip T35100C4D (Appendix A)
Software: Peakmaster 5.3with database of constituents by Takeshi Hirokawa
(http://web.natur.cuni.cz/gas/)
Procedure
1. Understand and identify the channel dimension and length of channel to detector
with reference to Micronitmicrofluidic chip (Appendix A)
2. Fixed an applied voltage for the test solution. *note the maximum voltage for ER
230 is 3000 V.
3. Varied the concentration of thebackground constituent (BGE)from 100mM to
1000 M. Choose Li+ , K+ and Na+ for cation and HCl, H2SO4 and HNO3 for anion
analysis. Observed the changes. *note that at least 5 points are needed
4. Recorded and export the signal level and separation time for cation, plot the
electropherograms of all concentration in a graph (for example a 3D graph).
Repeat the same for anion.
5. Choose a concentration of BGE to be used later for cation analysis in MS2
experiment.
6. Varied the voltage from 500 to2000 V with 500V increment.
7. Record the signal level and separation time versus applied electric field. (The
results will be compared to the electropherogram from experimental
measurement).
8. Find the electrophoreticvelocity and electrophoretic mobilityof the cation from the
prediction’s results.
9. Discuss the observations, which include parameters affecting ions movements
and characteristics of the electropherogram.
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Reference: example results of the test solution
Results for Cations
The electropherogram for the cations, run at 100 μM concentration, is shown in Figure P1. As
predicted by Peakmaster software, three negative peaks are observed. The peaks are negative
because the three cations Li+, K+ and Na+ are less conductive than the H+ cation they are
displacing in the background electrolyte. The electropherogram can be recorded with positive
peaks by selecting Invert in the C4D Amplifier window, in the Hardware Settings of the
PowerChrom software. Figure P1 shows the data with a sample injection time of 20 seconds.
Increasing the injection time, to 30 and 40 seconds, resulted in larger peaks but the separation of
the peaks was not as good.
Fig. P1 Electropherogram for cation
Results for Anions
Figure P2 shows the electropherogram for anion analysed at 1mM. This concentration will
overload the system, resulting in one large peak which cannot be resolved.
The solution for running anions should be diluted to 100 μM with deionised water. The
electropherogram is shown in Figure P2b. Peakmaster software predicts the two positive peaks
obtained, where the HSO4- and NO3- peaks cannot be resolved. Separating the anions under
these conditions will not produce an EOF peak, because the EOF travels away from the detector,
towards Reservoir 2
.
(a)
(b)
Fig. P2 The effect of concentration on the measured signal in electropherogram.
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MS2 MEMS (Experiment)
Microchip electrophoresis with C4D
The analysis of the EC20 Standard Test Solutions by microchip electrophoresis with
capacitively-coupled contactless conductivity detection (MCE-C4D ) will be performed.
Activities:
1. Based on the test solution provided, perform experiment of microchip
electrophoresis with capacitively-coupled contactless conductivity detection for
cations.
2. Investigate the effectssuch asinjection time and electric field (< 2000 V) on the
test sample.
3. Obtain the electrophoretic mobility and conductivity of the test solution
experimentally.
4. Report the experimental findings, which include: explanation of how injection,
separation and contactless conductivity measurement are achieved, the effects of
parameters affecting ion movements, difficulties faced in an actual measurement,
conclude on the method and findings in the experiment.
Injection, separation and detection
This section describes a procedure for a microchip electrophoresis experiment using a
floating injection. This type of injection requires control of the voltages at only two of the
fours reservoirs of the chip. Thus only one High Voltage Sequencer is needed.
During the floating injection step, 1000 V is applied across the chip (between reservoirs 1
and 3) (Figure E1 and more details in Appendix A).The channels of the chip are in a
double-T configuration, and this voltage fills the small area between the offset of the
channels. During the separation step, 1000 V is applied along the chip (between
reservoirs 2 and 4). This moves the sample towards the detector and reservoir 4,
separating the ions as they travel.
A gated injection can be performedwith the control of the voltage at all four reservoirs of
the chip (and thus needs two High Voltage Sequencers).
Fig. E1 Microchip layout
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1.
Equipment Required
ER255 or ER455 Microfluidic Chip Electrophoresis Kit (Fig. E2), including:
ER225 C4D Data System
ET225 Micronit Chip Electrophoresis Platform with C4D headstage
ER230 HV Sequencer (one or two units)
ET145-4 CE Microchip (45 mm) kit
PowerChrom and Sequencer software
EC20 Standard Test solutions
Background Electrolyte (BGE) = 0.5M acetic acid
Sample = 1mM LiCl, KNO3, Na2SO4in deionised water
One 20 - 200 μL pipette, with pipette tips
One syringe 5 mL
Deionised water
Lint-free tissues
Fig. E2 Micronit microfluidic chip, platform with C4D headstage, test solution, High
Voltage sequencer and C4D Data system.
.
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Experiment Procedures:
Precautions:
WARNING:
 ALWAYS ENSURE THE INSTRUMENT IS PROPERLY GROUNDED!
 DO NOT CONNECT THE POWER SUPPLY TO THE VOLTAGE TAP!
 NEVER CONNECT OR DISCONNECT ANY COMPONENT WHEN THE
INSTRUMENT IS POWERED ON.
 DO NOT OVER-TIGHTEN THE SCREWS (step 15)
Preparing the Hardware
1. Check you have all the components listed in the Equipment list
2. Check that the Sequencer software and PowerChrom software are installed on the computer.
Ensure
you
have
installed
the
latest
versions
of
softwares
from:
www.edaq.com/software_dnloads.html
3. Check that the High Voltage Sequencer (HVS) to the computer with a USB cable, as
described in the instruction manual. Do not turn it on yet.
4. Check that the C4D Data System is connected to the computer with a USB cable, as
described in the instruction manual. . Do not turn it on yet.
5. Check that the Chip Platform is connected to the C4D Data System using the DIN to HDMI
cable.
6. Check that the connections of the Chip Platform to the HVS using the coloured high voltage
cables areas shown in Table E1.
Table E1. Connecting the Chip Platform to the HVS

7.
8.
9.
10.
11.
Make sure you connect the correct black HVS cable to the HVS, as there are two of them.
If you are using 45 mm chips, you should use the black cable in the middle of the
platform.
 Connect the interlock cable between the Chip Platform and the HVS.
 Warning: the interlock is designed to disarm the HVS if the cover plate is lifted from the
Chip Platform. Do not try to bypass the interlock.
The microchip holder must be grounded to reduce noise in the C4D data signal. Use a green
ground cable to connect the ground connector on the Chip Platform to the green connector at
the back of the C4D Data System. Use a second cable to connect the green connector at the
back of the C4D Data System, to the green connector at the back of the
HVS.
The HVS can trigger the PowerChrom softwareto start recording. Use the red and black
trigger cable to connect the “CTL1 +” at the back of the HVS to the “TRIG +” at the back of the
C4D Data System. Connect the HVS “CTL1 –” to the C4D “TRIG –”.
Turn on the HVS. The driver will be installed if this is the first use.
Open the Sequencer software and ensure you are able to connect to the HVS by clicking on
the Online button at the top of the screen. You may need to go into the File, Preferences
menu to select the correct Connection Serial Port for the HVS. You can use the Serial Port
Monitor software (from the eDAQ website) to see which COM port the HVS is connected to.
Move and resize the Sequencer software screen so it occupies the left half of the screen.
Turn on the C4D Data System. The driver will be installed if this is the first use.
ENT4046 N/MEMS v5 131111
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12. Open the PowerChrom software. Ensure the software has setup the hardware unit; you
should see the Easy Access window, not the Hardware Unavailable window. Move and resize
the PowerChrom software screen so it occupies the right half of the screen.
13. Setup the trigger commands in the software packages as shown below:
a. Sequencer software: in the menu File, Preferences, select Contact Closure.
b. PowerChrom software: in the menu Edit, Preferences, Digital IO Settings, select External
Trigger Mode as Voltage Level (TTL).
c. PowerChrom software: in the Manual Sampling window, Inject Settings, select Wait for
Inject.
d. Sequencer software: in the later step, when you are setting up the sequence, remember
to select High/Closed, under Digital Output 1, during the separation step, as this will send
the trigger command. Also remember to select Low/Open in the very last step (after the
separation is complete).
14. Use gloves to place the empty microchip in the Chip Platform. Ensure that the four
circular C4D connectors lie on top of the four pins on the platform. Figure 2 shows a
microchip in the platform. Refer to user manual for ET225 Electrophoresis Platform for
details.
15. Place the reservoir cover on.
a. Ensure that the O-rings underneath the cover are in place and are dry; wipe with a tissue
if necessary.
b. Don’t turn the screws too tight(this will crack the microchip!); the screws should be turned
finger-tight.
c. Ensure that the reservoir cover is sitting flat and level with the base of the platform.
16. Place the cover plate on top of the platform. You may need to move the high voltage cables
slightly to ensure it is sitting flat and level with the base of the platform
Sequencer Software
17. Ensure the Sequencer software is open and in Online mode.
18. Setup a sequence as shown in either Table E2 for separating cations, or Table 3 for
separating anions. These use a Floating Injection.
Table E2. Sequence for separating cations using a Floating Injection
Table E3. Sequence for separating anions using a Floating Injection
PowerChrom Software and Pipetting Solutions
19. Ensure the PowerChrom software is open.
20. In the Easy Access window, click Manual Run.
21. In the Manual Sampling window, click Inject Settings and select Wait for Inject (Start
recording immediately) and OK.
22. In the Manual Sampling window, enter Stop sampling 2.00 min after Inject.
23. Click Hardware Settings. Enter the following settings and then OK:
 Sampling speed = 100/s
 Channel 1: Input = Input 1, Range = 50 mV
 Channel 2: Input = Off
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24. Click C4D Amplifier and enter the following settings:
 Low Pass = 5 Hz
 In Offset, click Zero (Rezero is needed when the settings are changed)
 Excitation frequency = 800 KHz, amplitude 100% (as initial values, this can be adjusted
later)
 Headstage gain, invert off
25. Dilute the sample from 1 mM to 100 μM with deionised water.
Figure E3. Pipetting solutions into the microchip reservoirs
26. Pipette 50 μL of the BGE into Reservoir 4. It should take less than one second for capillary
action to fill the channel with the solution. This can be confirmed by observing a change in
conductivity in the C4D signal.
 Keep the pipette vertical while pipetting solutions into the reservoirs.
 Make sure that the pipette tip gently touches the sloping walls of the reservoir, as you
deliver the solution. This will prevent the formation of an air bubble at the bottom of the
reservoir.
 Use different pipette tips when transferring the BGE and the sample to the reservoirs, and
when removing solutions from the reservoirs. This will avoid contaminating the solutions.
27. In the PowerChrom software:.
 If you already know the C4D settings for Frequency, Amplitude and Headstage Gain,
then enter these values now in the C4D Amplifier window, or
 If you don’t know the C4D settings, use the C4D Profiler to optimise the C4D settings, as
described in a separate application note. This must be done with BGE in the channel.
28. If separating cations, pipette 50 μL of the BGE into Reservoir 2 and Reservoir 3. Pipette 50
μL of the sample into Reservoir 1.
29. If separating anions, pipette 50 μL of the BGE into Reservoir 2. Pipette 50 μL of the sample
into Reservoir 1 and Reservoir 3.
30. Visually check that you have the same volume of solution in each of the reservoirs.
31. Place the cover plate onto the holder.
32. Click Zero in the Offset box.
33. You may need to select a smaller value for the Range at this point. Click OK twice to return
to the Manual Sampling window.
34. Arm the HVS by pressing and holding the red button on the front of the HVS unit.
35. You are now ready to analyse your sample. In the PowerChrom software, click “Start”.
36. In the Sequencer software, click “Run” to start the HVS sequence. This should trigger the
PowerChrom software to start recording.
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Procedure for Changing the Sample
1.
2.
3.
4.
5.
6.
7.
8.
Disarm the HVS.
Remove the cover plate from the platform.
Remove the sample from the sample reservoir using a pipette.
Flush the sample reservoir a few times using deionised water.
Pipette 50 μL of the new sample into the samplereservoir.
Replace the cover plate.
Arm the HVS.
Begin the analysis of the new sample.
Procedure for Removing the Microchip
1.
2.
3.
4.
5.
6.
7.
8.
Disarm the HVS.
Remove the cover plate from the platform.
Remove the solution from each of the reservoirs using a pipette.
To prevent formation of salt crystals inside the channel during storage, pipette
deionised water into each of the reservoirs.
Flush the microchip by placing the syringe into the Reservoir 4 and gently pressing
on the syringe, holding the pressure for ten seconds.
Remove the deionised water from each of the reservoirs using a pipette.
Remove the reservoir cover and dry the o-rings underneath the cover using a tissue.
Remove the chip.
Notes
It is sometimes necessary to filter the BGE and sample solutions to prevent particles from
blocking the narrow channel of the chip. This can be achieved by using a filter which fits onto
the end of the syringe.
It may also be necessary to place the BGE and sample solutions in an ultra-sonic bath to
remove any dissolved air in the solutions. Dissolved air can cause the formation of air bubbles
in the channel, which can result in an electric arc when the high voltage is applied. This
produces high temperatures in the channel which can damage the channel of the chip.
Observing the current flowing through the channel of the chip can be useful when developing
a method. This current is displayed in the Sequencer software, and it can be recorded from
the monitor connectors at the back of the HVS. If the current reads zero, or is very noisy,
during the separation step, this suggests there is an air bubble in channel.
If the channel of the chip becomes blocked with particles, it may be possible to clear the
obstruction, either by injecting air into one end of the channel using a syringe, or by using a
weak vacuum at one end of the channel. Use a lint-free tissues, as opposed to normal
tissues, to prevent particles from blocking the channel of the chip.
If the sample peaks get progressively smaller over successive runs, this may be due to the
depletion of ions in the sample reservoir close to the start of the channel. You can mix the
sample in the reservoir, by using a pipette to suck the sample in and out of the pipette a few
times.
If the baseline begins to drift a lot during the analysis, it may be useful to flush the chip using
the syringe. Place the syringe into the outlet reservoir and gently press on the syringe and
hold the pressure for ten seconds.
You may have to the alter the Offset and change the Range several times during a series of
runs, but do NOT alter the Frequency, Amplitude or Headstage Gain settings until you have
completed all the calibration and sample runs in an experiment.
Cleaning and Storing the Chip
The chip can be rinsed and emptied while it is still in the Chip Platform. This is done by
pushing the nozzle of a syringe into the sloping reservoir holes of the reservoir cover and
gently pushing on the plunger to apply pressure.
Alternatively, this can be done with the chip removed from the Chip Platform, by using a
syringe with a rubber O-ring connected to its nozzle. To make this device, cut most of the
nozzle from a syringe and glue a rubber O-ring to the end of the syringe. The O-ring is then
pushed down onto the glass surface of the chip above the reservoir. The plunger is gently
pushed to force liquid or air through the channel of the chip.
For the optimum performance, the chip should be properly treated after use to clean the glass
surface and restore the EOF properties. Please follow the instructions provided by the chip
manufacturer (Appendix B).
References
1. EDAQ Application Note C4D 016.
2. VladislavDolník, Shaorong Liu, Stevan Jovanovich, Capillary electrophoresis on
microchip, Electrophoresis, Volume 21, Issue 1, pages 41–54, 1 January 2000
3. Pavel Kuban and Peter C. Hauser , A review of the recent achievements in
capacitivelycoupled contactless conductivity detection,AnalyticaChimicaActa
607 ( 2008 ) 15–29.
4. Pavel Kuban and Peter C. Hauser, Capacitively coupled contactless
conductivity detection for microseparation techniques – recent developments,
Electrophoresis 2011, 32, 30–42
Appendices
Appendix A: Specificationdocument T35100C4D chip
Appendix B: Cleaning and reconditioning procedure X35100C4D microchips
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Appendix A: Specificationdocument T35100C4D chip
Chip:
Material: D263 T borosilicate glass
Chip size (w x h): 15.0 x 45.0 +/-0.3 mm
Thickness: 1.1 +/-0.050 mm cover and 0.100 +/-0.015 mm bottom
On-chip reservoir volume: <1 µL
Channels:
Width: 100 +/-5 µm
Depth: 10.0 +/-0.5 µm
Length of the double-T: 100 µm between center lines
Channel length (2-4): 40 mm
Separation length: 33 mm
Cross Arm length: 9 mm
Electrodes:
Material: platinum, tantalum adhesion layer deposited on the bottom surface
Electrode thickness: 200 nm
Size (w x h): 200 x 500 µm
Distance between excitation and detection electrode: 250 µm
Distance between electrode pairs: 2.9 mm
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Appendix B: Cleaning and reconditioning procedure X35100C4D microchips
In order to be able to reuse without degradation of the performance it is critical that the chips
are properly treated after use. Store the chips only in buffer solution for one day maximum.
Do not store chips in deionized water. To obtain repeatable results clean the chips at the end
of a series of experiments. In order to store the chips for a longer period the cleaning
procedure should be carried out first. Only use a hotplate to dry the chips. Do not let the chips
dry out in the air.
Flushing procedure with the chip removed from the holder
• Remove the sample and the buffer from the chip
• Remove the chip from the holder,
• Add deionized water into all four reservoirs (5 μL)
• Apply a pressure on the reservoir closest to the electrodes using a syringe with o-ring
To keep the microchip in condition (for a maximum of one day):
• Perform an experiment
• Flush the chip with buffer (2 times)
• Store the chip in the buffer
To clean a chip after the experiments:
• Flush the chip with demineralized water just after the experiment (2 times)
• Remove the chip from the holder
• Flush the chip with 1 mol/L NaOH (2 times, note: concentrated NaOH damages the
plastic in the holder)
• Pipette 1 mol/L NaOH (5 μL) into all reservoirs and wait for 5 minutes
• Flush the chip with demineralized water (2 times)
• Heat the chip at 250°C on a hotplate for at least one hour (for the X80100C4D at least
two hours)
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Marking Scheme
Lab
(10%)
Assessment
Components
Hands-On
&
Efforts (2%)
On the Spot
Evaluation
(2%)
Lab Report
(6%)
Details
The hands-on capability of the students and their efforts during the
lab sessions will be assessed.
The students will be evaluated on the spot based on the lab
experiments
Each student will have to submit his/her lab final reports (MS1 and
MS2) within 7 days of performing the lab experiment. The report
should consist of the followings with emphasis on the corresponding
activities (i.e. prediction for MS1 and experiment on MS2)
1. Introduction: short notes on concept and theory of microchip
electrophoresis with contactless conductivity measurement.
2. Experimental: general summary of the prediction (for MS1)
orexperiment work (for MS2).
3. Results and Discussions: measurement results, analysis, and
evaluations, with neat graphs/images of the results and
recorded data; and a comparison with prediction in MS1 and
experimental results in MS2.
4. Conclusion: conclude on the findings.
5. References, which includes all the technical references cited
throughout the entire lab report.
The report must have references taken from online scientific journals
(e.g. www.sciencedirect.com,
http://ieeexplore.ieee.org/xpl/periodicals.jsp,
http://www.aip.org/pubs/) and/or conference proceedings (e.g.
http://ieeexplore.ieee.org/xpl/conferences.jsp).
Format of references: The references to scientific journals and text
books should follow following standard format as stated in :
http://foe.mmu.edu.my/v3/main/undergrad/fyp_report_guidelines.html
Reports must be typed and single-spaced, and adopt a 12-point
Times New Roman font for normal texts in the report.
Any student found plagiarizing their reports will have the assessment
marks for this component (6%) forfeited.
The lab report has to be submitted to the Nanolab staff. Please make
sure you sign the student list for your submission. No plagiarism is
allowed. Although the electrical characteristics of the measured
sample from the same group can be similar, the report write-up
cannot be duplicated for group members. The individual report has to
be submitted within 7 days from the date of your lab session. Late
submission is strictly not allowed.
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