Integrated System Build & Test
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During this phase the team hoped to get a separation of cells using dielectrophoresis. This was an overly optimistic goal, as microfabrication is sensitive and we needed time to work out the kinks and details.
The team actually did move 1um polystyrene particles using dielectrophoresis in a channel which uses the fabrication method by which we plan to use in the product's end state. This alone was a small success. As we progress with our microfabrication, we should ensure less hurdles (such as seals breaking, fluid leaking, etc.) which should allow us to perform the experiments on cells instead of just particles. This will come with the next phase.
ER4 - Variable VoltageCurrently the voltage is able to reach 24VAC this will be improved once rectifier transformer testing is finished.
ER5 - Variable FrequencyER 5 - Variable Frequency
ER6 - Use Wall Outlet for PowerCurrently every electrical component can be powered by a 120V wall outlet.
ER7 - Accurate TimerTimer was tested add was accurate for a 1 hour run time. This needs to be tested again on an microprocessor that is running with multiple functions.
ER8 - Emergency Shut offThe button has been tested and works as expected.
ER10 - Maximum CurrentThe maximum current is currently measuring below 15mA.
ER24 - Number of User InputsThe user currently will be have have 12 inputs to set before the device will begin. The power switch (1), setting the voltages (2), setting the frequency(2), controlling the motors(2), the start button(1), the emergency stop(1),and the electrode safety switch(1).
Stepper MotorSlides of Pictures and Videos
Risk and Problem Tracking
Functional Demo Materials
1:15mL Tube Rests 2:Microchannel Support 3:Syringe Pump 4:Electrode Wire Terminal Block 5:Fluid Flow Rate Display 6:Frequency Generator 7:Voltage and Current Display 8:Emergency Stop 9:Voltage Control 10:Start Button 11:Fluid Flow Control 12:Syringe Pump Wire Hole
- 1) 15mL Tube Rests needed to be resized to a 3/4" diameter
- 6) Frequency Generator frequency control knob hole was shifted to the left 1/8"
- 11) Fluid Flow Control holes will need to be resized to fit push-button switches
- 10) Start Button hole needed to be reamed for button to fit
- Not shown) Hole for Power Entry Module was changed due to change in part
- Not shown) Holes for stepper motor control switches need to be added
- Not shown) During bending the part broke at the seam, seams will now be welded in order to make the shell
Channel SealWith electrodes spaced 250 um from the channel, some leakage occurred primarily around the perpendicular electrode. Electrode slits were cut with an X-Acto knife.
With electrodes spaced 350 um from the channel, some leakage occurred around the electrodes. In this case, electrode slits were also cut with an X-Acto knife. Because of the leakage that occurred, a new method of cutting electrode slits needed to be found.
Leaking between outlet channel and perpendicular electrode with 350 um spacing from channel. Particles fluoresce green, better showing the leak
Leaking to the right of the parallel electrode in the channel with 350 um electrode spacing. Particles fluoresce green, better showing the leak
1 um Particle eDEPFor this experiment, a microchannel with electrodes spacing 350 um from the channel was used. To cut electrode slits, a 1 mm biopsy punch was used to create 1 mm x 5 mm ovular cuts. The channel seal can be seen in the video below. Some leakage occurs between both electrodes and the outlet channels, however overall the channel seal is much better than in previous trials.
The log of DEP tests can be found below.
With a 5 kHz 10 Vpp sine wave, no DEP could be observed.
With a 5 kHz 40 Vpp sine wave, some negative DEP force was seen (particles traveling from the perpendicular to the parallel electrode).
With a 10 kHz 40 Vpp sine wave, little to no negative DEP force was seen. However, at this point it appears the channel was damaged from repeated movement of the electrodes. Testing at this set of conditions will be repeated.
Plans for next phase
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