enzyme biosensor
Post on 01-Jan-2016
30 Views
Preview:
DESCRIPTION
TRANSCRIPT
Presentation Overview
Enzyme BiosensorDetection of glycerides in biodiesel1Team Members:Ben WilsonMatt YourekMegan TempletonMentors: Dr. Tom Hess Dr. Dev ShresthaClient: Dr. Dev Shrestha
Presentation OverviewOpportunity Statement
Current Testing Method
Product Specifications
Housing Design
Circuit Design
Membrane
Experimentation
Experimental Design
Parameter Measurements
Results
RecommendationsOpportunity StatementDesign, 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.3
Current Testing MethodCurrently 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.4
Product SpecificationsLight weight total weight of less than 5lbs
Small have a footprint smaller than half a sheet of paper
Durable able to withstand drops and bumps
Reusable can test multiple samples with one membrane
Fast easily calculates concentration percent in seconds
Simple minimal buttons and good user feedback
Accurate Consistent voltage signal for each sample
Easy to Calibrate a single button push resets reference voltageHousing DesignFabricated using the Mechanical Engineering Department ABS plastic rapid prototype printer
3/16 wall thickness
1 x 6 x 3.5 internal space
Six attachment points
Separate battery compartment
Circuit board attachment points
Circuit DesignMajor Components
Op Amps
RC Filter
Arduino UNO
Circuit DesignLM741CN
Simple operational amplifier
Forces voltage signal to be positive by adding a constant voltage to the measured signal
AD623AN
Variable gain operational amplifier
Amplifies voltage signal so small changes can be recognized by the ArduinoCircuit DesignRC Filter
Uses a resistor and a capacitor in series to filter the signal
Removes high frequency signal noise added during amplification
The cutoff frequency (Hz) is calculated using the equation
Circuit DesignArduino UNO
Registers user input through buttons
Reads voltage from probe and assigns bit value to corresponding variable
Blinks LED to verify that a button has been pushed
Writes valuable information to LCD screen
Processes input voltage from probe by removing the added voltage and converting to concentration percent
Circuit Design
Circuit DesignThe Biosensor was calibrated using a DC voltage source and a digital multimeter
A line was then fit to the data using the Matlab fitting tool
The calibration equation was then programmed into the Arduino, so the true signal voltage is displayed
MembraneInitially going to test three types of membranesPVAPVDFWater emulsion
MembraneMembrane Failure
In the beginning the membrane easily degraded
Then even the thinnest layers of membrane were too thick to record accurate measurements
Determined to add lipase directly to solution
ExperimentationRan 32 experiments testing four variables:
Feedstock
Lipase
Temperature
Soap
Feed - Oil - Biodiesel Temp. - 20C - 40C Lipase - 20 mg - 10 mg Soap - 1 ml - no soap
VariablesANOVA - Identify significant variables
Regression Analysis - Identify optimal combinations
Calibration
Experimental Design Initial pH
Initial mV
Final pH
Final mV
pH
mV Point Measurements:Time-based Sampling:Parameter MeasurementsSignificant Variable: Optimal Combination:Feedstock 20 mg lipase, 20C, 1 ml soapResultsSampleFeedDimensionless ValuemV1Canola Oil015.92Canola Oil08.0330 min. Biodiesel0.546.7430 min. Biodiesel0.549.0560 min. Biodiesel 191.1660 min. Biodiesel 1101.0RecommendationsConstruct calibration curve from biodiesel samples with known concentration of total glycerides. True concentration is determined by gas chromatography (GC)
Validate curve with GC analysis
Gain better understanding of reaction mechanism driving the pH change
Determine membrane composition and thickness having the least impact on probe sensitivity
Questions?
top related