FACULTY OF ENGINEERING

LAB SHEET

NANO/MICRO-ELECTROMECHANICAL SYSTEMS(N/MEMS)

ENT4046

TRIMESTER II (2012/2013)

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 with capacitively-coupled contactless conductivity detection

Objectives After completing the two laboratory phases on microchip electrophoresis (MCE) with capacitively-coupled 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 chip for injection, separation, transportation and characterization. The configuration has the advantages of 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 electric field. 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 Ze and 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 Ze and 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 F el.

The electric force is simply F el=Ze E. 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=−6auep, balances F el,

F total=Fel+Fdrag=0 (1)

uep=Ze6aE=μionE (2)

where the proportionality constant μion=Ze6a is called the ionic or electrophoretic mobility,

(-ve for anions) (cm2·(V·s)-1)uep is the electrophoretic velocity or migration rate (cm·s-1),E is 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 the ion.

a=kBT6D (3)

where kB is the Boltzmann constant, and T is the temperature, D is the diffusion coefficient.

The electrophoretic mobility can be determined experimentally from the migration time and the field strength:

μion=( Lt r

)(LtV

) (4)

where L is the distance from the inlet to the detection point, t r is the time required for the analyte to reach the detection point (migration time),V is the applied voltage (field strength), and Lt 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 σ ion

σ ion=Zecion μion (5)

wherec ion 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 100 mol/m3, 1 mol contains NA or 6.02214 ×1023 atoms or molecules)

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(c)

(a)

(b)

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 aqueoussolutions 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 by uo=μo E.

After injection and separation, analytes in electrophoresis process can be detected by various methods, namely optical 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.

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 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.

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(a)

(b)

(c)

In capactively coupled contactless conductivity measurements an AC-voltage is applied to one of the galvanically isolated electrodes and the resulting AC-current is measured at the second electrode. This is possible as the electrodes form capacitors 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, and bio-molecules. An example for measurement of inorganic cation in blood sample is shown in Figure 5.

Fig. 4 (a) Schematic drawing of a C4D cell for conventional capillary electro-phoresis. (b) Simplified equivalent circuit diagram in presence of direct capacitive coupling between the electrodes. (c) Schematic drawing of contactless conductivity detection for microchip electrophoresis.

Fig. 5 Determination of inorganic cations in blood serum sample using MCE-C4D . Electrolyte solution, 15 mM L-arginine, 10.90 mM maleic acid, 1.5 mM 18-crown-6 (pH 5.85). (A) Blood serum sample (diluted 1:50), (B) blood serum sample spiked with 1.5 mM Li1 (diluted 1:50).

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MS1 PredictionMicrochip electrophoresis with C4D

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 of background electrolyte or analytes (cation and anions).

Test solution:Background electrolytes (BGE) = 0.5 M acetic acidSample = 1 mM LiCl, KNO3, Na2SO4 in deionised water

Micronit microfluidic chip T35100C4D (Appendix A) Software: Peakmaster 5.3 with 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 Micronit microfluidic 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 the background constituent (BGE) from 100 mM 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 to 2000 V with 500 V 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 electrophoretic velocity and electrophoretic mobility of 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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(a) (b)

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 AnionsFigure P2 shows the electropherogram for anion analysed at 1 mM. 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.

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 effects such as injection 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 detectionThis 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 performed with 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 SystemET225 Micronit Chip Electrophoresis Platform with C4D headstageER230 HV Sequencer (one or two units)ET145-4 CE Microchip (45 mm) kit

PowerChrom and Sequencer softwareEC20 Standard Test solutions

Background Electrolyte (BGE) = 0.5 M acetic acidSample = 1mM LiCl, KNO3, Na2SO4 in 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 Hardware1. Check you have all the components listed in the Equipment list2. 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 are as shown in Table E1.

Table E1. Connecting the Chip Platform to the HVS

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.7. 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 theHVS.

8. The HVS can trigger the PowerChrom software to 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 –”.

9. Turn on the HVS. The driver will be installed if this is the first use.10. 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.

11. Turn on the C4D Data System. The driver will be installed if this is the first use.

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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 Software17. 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 Solutions19. 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 Sample1. Disarm the HVS.2. Remove the cover plate from the platform.3. Remove the sample from the sample reservoir using a pipette.4. Flush the sample reservoir a few times using deionised water.5. Pipette 50 μL of the new sample into the sample reservoir.6. Replace the cover plate.7. Arm the HVS.8. Begin the analysis of the new sample.

Procedure for Removing the Microchip1. Disarm the HVS. 2. Remove the cover plate from the platform.3. Remove the solution from each of the reservoirs using a pipette.4. To prevent formation of salt crystals inside the channel during storage, pipette

deionised water into each of the reservoirs.5. Flush the microchip by placing the syringe into the Reservoir 4 and gently pressing

on the syringe, holding the pressure for ten seconds.6. Remove the deionised water from each of the reservoirs using a pipette.7. Remove the reservoir cover and dry the o-rings underneath the cover using a tissue.8. Remove the chip.

NotesIt 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. Vladislav Dolník, Shaorong Liu, Stevan Jovanovich, Capillary electrophoresis on

microchip, Electrophoresis, Volume 21, Issue 1, pages 41–54, 1 January 20003. Pavel Kuban and Peter C. Hauser , A review of the recent achievements in

capacitively coupled contactless conductivity detection, Analytica Chimica Acta 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: Specification document T35100C4D chipAppendix B: Cleaning and reconditioning procedure X35100C4D microchips

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Appendix A: Specification document 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

Details

Hands-On & Efforts (2%)

The hands-on capability of the students and their efforts during the lab sessions will be assessed.

On the Spot Evaluation (2%)

The students will be evaluated on the spot based on the lab experiments

Lab Report(6%)

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) or experiment 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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