CHEMICAL PRE-CONCENTRATOR FOR TRANSDERMAL ALCOHOL

MONITORING(CPTAM)

Mid-Semester Presentation

February 28, 2012

TEAM MEMBERS

Josh GwinnTeam LeaderProgramming

Amplifier Circuit

Lakeldren WilliamsWeb Design

Programming

Robert DaleMechanical Design

Hardware Debugging

James Akio CottonPCB Design

Hardware Debugging

OUTLINE

Problem Solution System Overview Constraints

TechnicalPractical

Bill of Materials Improvements Testing PCB

PROBLEM To further his research, Dr. Todd Mlsna

with MSU’s Chemistry Department requires a concentrator that heats a sample before measuring alcohol content.

SOLUTION CPTAM

Heat sampleRecord temperaturePump mixture through alcohol sensorRecord alcohol sensor

Alcohol Sensor

AlcoholMixture

Vacuum Pump

Exhaust

Capillary Tube

SYSTEM OVERVIEW

Data Storage

PumpTemperature

SensorUser DefinedParameters

Alcohol Sensor

Amplifier Circuit

Microcontroller

TECHNICAL CONSTRAINTSName Description

Temperature of Capillary Tube The temperature of the capillary tube must be maintained at ± 20ºC of the user-defined temperature.

Temperature Sensor Range The temperature sensor must be able to sense temperatures ranging from 15ºC to 200ºC.

Power Supply The CPTAM must operate from a standard 120V wall outlet.

Accuracy The CPTAM must record the alcohol sensor output within a 5% degree of accuracy.

Memory The temperature of the capillary tube and the alcohol content must be recorded three times per second for a programmable amount of time.

PRACTICAL CONSTRAINTSType Name Description

Social Simple This device must be easy to set up and use by anyone with average technical skills.

Manufacturability Customization Users must be able to program heating temperature, collection time, and pump power.

SOCIAL Must be able to set up and use with

average technical skillsA Research DeviceMultiple Users Differing Educations and Experiences

[1]

MANUFACTURABILITY Customization

Heating TemperatureCollection TimePump Power

Fine Tuning

[2]

BILL OF MATERIALS

BILL OF MATERIALS

IMPROVEMENTS

60A MosFet’s Temperature Sensor

Narrower field of View Added surface mount resistors for

precision Removed current limiting resistors Added current sensing resistor

Removed optional paths for current Digital Potentiometer and Opamp

DIGITAL POTENTIOMETER AND OPAMP

MCP41050

TESTING PCB

Visual defects Power Supply

Test the various voltages○ 5V regulator caused noise on the 12V rail

Needed cap

Temperature Sensor

INFRARED SENSOR I2C

Sensor returned 3A2F = 14,895 Temp = 14,895*0.02 – 273 = 24.9ºC

TESTING Microprocessor

Test the UART connections

Test heating of the tubeCheck voltage quality

Test the current sensing circuitNeeded low pass filter

PumpBlown mosfet

Alcohol Sensor, Amplifier Circuit Verify that voltages are within 0-3.3V

VDIP1Verify initialization checks

VDIP1

From hex to ASCII:09h 20h 74h 65h 73h 74h 2Eh 63h 73h

76h 0Dh

[Tab][Space] t e s t . c s v [CR]

PCB

Power Traces4 connectors2 mosfets

Different Power Rails

Digital Potentiometer

Manual Potentiometer

Lm6484 Opamp

PCB

Power Traces

PCB

Digital Potentiometer

PCB

Lm6484 Opamp

REFERENCES [1] Jackie Brown Medical. [Online]. Available:

http://www.jackiebrownmedical.ie/medical-jobs-blog/tag/lab-technicians/ . [Accessed September 27, 2011]. [2] CTI Career Search. [Online]. Available:

http://www.citytowninfo.com/employment/medical-lab-technicians . [Accessed September 27, 2011]. [3] Newegg. [Online]. Available:

http://www.newegg.com/Store/SubCategory.aspx?SubCategory=58&name=Power-Supplies. [Accessed September 27, 2011].

[4] Omega. [Online]. Available: http://www.omega.com/Heaters/pdf/fgr.pdf. [Accessed September 27, 2011].

[5] Arstech. [Online]. Available: http://www.arstech.com/item-External-Power-Supply-3-3V-pwr3v.html. [Accessed September 27, 2011].

[6] Pololu. [Online]. Available: http://www.pololu.com/catalog/product/1061. [Accessed September 27, 2011].

[7] Omega. [Online]. Available: http://www.omega.com/pptst/IRCO_CHAL_P13R_P10R.html. [Accessed September 27, 2011].

[8] Digi-key. [Online]. Available: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MAX6675ISA%2B-ND. [Accessed September 27, 2011].

[9] Digi-key. [Online]. Available: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM741CNNS-ND. [Accessed September 27, 2011].

[10] Digi-key. [Online]. Available: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LTC1051CN8%23PBF-ND. [Accessed September 27, 2011].

CHEMICAL PRE-CONCENTRATOR FOR TRANSDERMAL ALCOHOL

MONITORING(CPTAM)

Mid-semester Presentation

February 28, 2012