Transcript Enzyme Biosensor

Detection of glycerides in biodiesel
Team Members:
Ben Wilson
Matt Yourek
Megan Templeton
Mentor: Dr. Tom Hess
Client: Dr. Dev Shrestha
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Design, fabricate, and test a handheld biosensor that
uses a modified pH meter combined with an
immobilized enzyme electrode to detect the amount of
free and total glycerol in a sample of biodiesel.
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Currently biodiesel makers use a gas chromatograph to
measure the amount of glycerol within their biodiesel. While
the GC provides a very accurate measurement, it is a time
consuming process to prepare and test a sample.
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Blood glucose meters
Blood pressure sensors
i-Spec Q-100
- uses impedance spectroscopy technology, which is
similar to infrared spectroscopy
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Small
Light
Fast response time
Simple to use
Accurate
Easy to calibrate
Reusable
Strong/Durable
Inexpensive
Sensitive to small changes in pH
User friendly
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Dimensions ≤ 8”x 6”x 5”
Weight of about 2 lbs
Response time of 10 minutes or less
Able to test four samples in one hour
Error margin of 5% of concentration measurement
Can withstand repeated drops from 5ft
Does not bend or flex
Storage for electrode
Result is automatically displayed in large numbers
Total of five buttons or less
Visual or audio signal when measurement is complete
Audio signal on button push
Large buttons that take < 3.5lbf to push
Matte/textured finish for added grip
Battery operated
Takes user < 5 minutes to change electrode
Automatic zeroing upon button push
Visual or audio signal for low battery
One electrode can be used up to 50 times
Costs less than $300 to fabricate
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Pros:
 Very similar to pH meter
 Easy to store membrane
Cons:
 Higher chance of damage to
electrode
 Could experience bad connection
between electrode and instrument
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Pros:
 Simple to use
 Doesn’t need to be held
Cons:
 Would need to be more
durable/sealed
 More complicated to
wash and store
membrane
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Gelatin-Lipase membrane
- cited in literature research paper
PVA membrane
- found during membrane research
PVDF membrane
- found during membrane research
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Gelatin-Lipase Membrane
Pros:
 Easy to make
 Similar testing published in papers
Cons:
 Published paper does not include all information
 Membrane falls apart in storage buffer and water
 Does not give reliable mV readings
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PVA Membrane
Pros:
 Mechanically strong and flexible
 Resistant to oil and solvent
 Has ionic conductivity that allows easy flow of electrons
 Used in a biosensor to detect glycerides
Cons:
 Complex process to create membrane
 Water-soluble, so it might dissolve during reaction
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PVDF Membrane
Pros:
 Resistant to acids, bases, and solvents
 Mechanically strong
 Low cost
Cons:
 Requires very advanced equipment/techniques
 A detailed process to create
 Used for the growth of neurons, not typically used with
a biosensor
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Tested both pure canola oil and a biodiesel sample
using the gelatin-lipase membrane
The following graphs are the results of millivolt change
during the testing process
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Pure canola oil sample
Peak to peak average = 22 mV
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Biodiesel 30 minute sample (Part 1)
Peak to peak average = 18 mV
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Biodiesel 30 minute sample (Part 2)
Peak to peak average = 18 mV
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Using the estimated peak to peak value for each test, as
well as the glyceride percent concentration we can
obtain the following two point calibration
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Arduino UNO with ATmega328
Pros:
 Easy to use/program
 Comes in design kits
 Lots of memory
 LCD screen comes with wiring instructions for Arduino
Cons:
 New programming language to learn
 Minimum voltage input of 6V
 Slower clock rate
 Problems could be made worse by mass of online
information
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PICAXE 14M2
Pros:
 Familiar programming language
 Faster clock rate
 Dr. Wolbrecht teaches a class that uses them
Cons:
 Manufactured and distributed from UK
 Not much programming help/information
 Less memory
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Instrument
- Design 1, external electrode design
Membrane
- N/A
Microcontroller
- Option 1, Arduino UNO with ATmega328
LCD screen
- hacktronics LCD screen, comes with Arduino wiring
Housing material
- ABS 3D printed plastic
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Creation and testing of PVA and PVDF membranes
Effect of multiple layers of cellulose acetate solution on
reaction time and membrane preservation
Relation of mV amplitude to concentration percent
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Nov 30 – Dec 9: Testing of gelatin-lipase membrane
Dec 2: Snapshot
Dec 6: Design review
Christmas Break
Jan 17 – Jan 25: Testing of PVA membrane
Jan 26 – Feb 7: Testing of PVDF membrane
Feb 8 – Feb 24: Finishing touches on design and
ordering of any parts
Feb 27 – Mar 9: Fabrication
Spring Break
Mar 19 – Apr 26: Validation
Apr 27: Engineering Expo
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Materials for Membranes: $561
Misc. Chemicals: $500
Microcontroller: $90
LCD Screen: $11
Misc. Electronics: $50
Housing: $300
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Total: $1512
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Ben Wilson – Mechanical Enginner
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Matt Yourek – Biological and Agricultural Engineer
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Megan Templeton – Biological and Agricultural
Engineer
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