TO INDICATE TOXIC LEVEL OF AMMONIA USING CARBON-

NANOTUBE SENSORS

BY:

AAKASH MHANKALE-803000470 DEEKSHA SIVAKUMER-

893513473 PRIYANKA NARASIMHA

REDDY-803019033 ROHAN MEHTA-802954974

INTRODUCTION• OUR RESEARCH PAPER FOCUSES ON THE DETECTION

OF AMMONIA USING CNT SENSORS AND ITS TOXIC EFFECTS ON HUMAN AND POULTRY HEALTH.

• ALSO, FOCUSES ON THE INDUSTRIAL APPLICATION AREAS OF AMMONIA SENSORS.

HEALTH EFFECTS OF AMMONIA

•HUMAN HEALTH

GASTROINTESTINAL DISORDER

DAMAGE TO THE EYES

LESIONS IN THE CORNEA

SKIN BURNS

NASAL IRRITATION

•POULTRY

DAMAGE TO THE RESPIRATORY SYSTEM

DAMAGE TO THE EYES

LESIONS IN THE CORNEA

NEWCASTLE DISEASE

APPLICATIONS AREAS OF AMMONIA SENSORS

• ENVIRONMENTAL GAS ANALYSIS

• AUTOMOTIVE INDUSTRY

• CHEMICAL INDUSTRY

• MEDICAL APPLICATIONS FOR AMMONIA SENSORS

TYPES OF RESPIRATORS USED IN INDUSTRIES

• DISPOSABLE PARTICULATE RESPIRATORS

• CHEMICAL CARTRIDGE RESPIRATORS

• POWERED AIR-PURIFYING RESPIRATORS

• SCBA OR SELF-CONTAINED BREATHING APPARATUS UNITS

WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO PROTECT

HUMAN HEALTH?• THE FEDERAL GOVERNMENT DEVELOPS REGULATIONS AND RECOMMENDATIONS TO PROTECT

PUBLIC HEALTH.

• THE EPA, THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA), AND THE FOOD AND DRUG ADMINISTRATION (FDA), THE AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY (ATSDR) AND THE NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH (NIOSH) ARE SOME FEDERAL AGENCIES THAT DEVELOP REGULATIONS FOR TOXIC SUBSTANCES.

• OSHA HAS SET AN 8-HOUR EXPOSURE LIMIT OF 25PPM AND A SHORT-TERM (15-MINUTE) EXPOSURE LIMIT OF 35PPM FOR AMMONIA IN THE WORKPLACE.

• NIOSH RECOMMENDS THAT THE LEVEL IN WORKROOM AIR BE LIMITED TO 50PPM FOR 5 MINUTES OF EXPOSURE.

GAS SENSORS

• GAS SENSORS HAVE ATTRACTED INTENSIVE RESEARCH INTEREST DUE TO THE DEMAND OF SENSITIVE, FAST RESPONSE, AND STABLE SENSORS FOR INDUSTRY, ENVIRONMENTAL MONITORING, BIOMEDICINE.

• NANOTECHNOLOGY HAS CREATED HUGE POTENTIAL TO BUILD HIGHLY SENSITIVE, LOW COST, PORTABLE SENSORS WITH LOW POWER CONSUMPTION.

• HIGH SURFACE-TO-VOLUME RATIO AND HOLLOW STRUCTURE OF NANOMATERIALS IS IDEAL CONCEPT FOR THE ADSORPTION OF GAS MOLECULES. GAS SENSORS BASED ON NANOMATERIALS, SUCH AS CARBON NANOTUBES (CNTS), NANOWIRES, NANOFIBERS, AND NANOPARTICLES ARE USED WIDELY.

BASIC CRITERIA FOR GOOD AND EFFICIENT GAS SENSING SYSTEMS

• HIGH SENSITIVITY AND SELECTIVITY.

• FAST RESPONSE TIME AND RECOVERY TIME.

• LOW ANALYST CONSUMPTION.

• LOW OPERATING TEMPERATURE AND TEMPERATURE INDEPENDENCE.

• STABILITY IN PERFORMANCES.

CARBON NANO TUBESTHERE ARE TWO TYPES OF NANOTUBES:

• SINGLE-WALLED CARBON NANOTUBES (SWCNTS) : ONE-ATOM-THICK LAYER OF GRAPHITE ROLLED UP INTO A SEAMLESS CYLINDER WITH A DIAMETER OF SEVERAL NANOMETERS.

• MULTIWALLED CARBON NANOTUBES (MWCNTS): CONSIST OF MULTIPLE LAYERS OF GRAPHITE WRAPPED UP TOGETHER TO FORM A TUBE SHAPE, SHARING THE SAME CENTRAL AXIS.

PROPERTIES OF CARBON NANO TUBES

• MECHANICAL: CNTS ARE THE STRONGEST AND STIFFEST FIBERS THAT ARE KNOWN CURRENTLY DUE TO THE C–C BOND.

• THERMAL: CNTS HAVE HIGH THERMAL STABILITY IN BOTH VACUUM AND AIR.

• ELECTRICAL: CNTS CAN BE EITHER METALLIC OR SEMICONDUCTING, DEPENDING UPON THE TUBE DIAMETER AND THE CHIRALITY (THE DIRECTION IN WHICH THE GRAPHITE SHEET IS ROLLED TO FORM THE TUBE)

• NANOTUBES WITH  ( BEING A NONZERO INTEGER) ARE METALLIC WHILE ALL THE OTHERS ARE SEMICONDUCTING.

• DIELECTRIC: THIS PROPERTY OF NANOTUBES IS HIGHLY ANISOTROPIC DUE TO THEIR NEARLY ONE-DIMENSIONAL STRUCTURES, WHICH MAY ENABLE NANOTUBES TO CARRY HIGH CURRENTS WITH NEGLIGIBLE HEATING EFFECT

STRUCTURES OF CARBON NANOTUBE• ARMCHAIR SWCNT’S• ZIGZAG SWCNT’S• CHIRAL SWCNT’S

SYNTHESIS OF CARBON NANOTUBES

• ELECTRIC ARC DISCHARGE METHOD TWO GRAPHITE RODS( ANODE AND

CATHODE) ARE PLACED IN AN ENCLOSURE THAT IS FILLED WITH INERT GAS(HELIUM OR ARGON).

ANODE IS MOVED TOWARDS CATHODE UNTIL AN ARC APPEARS

ON COOLING OR DE-PRESSURING, NANOTUBES WITH THEIR BY PRODUCTS WILL BE COLLECTED.

• LASER ABLATION METHOD

LASER PULSES ABLATE A CARBON TARGET PLACED IN TUBE FURNACE.

INERT GASES SUCH AS HELIUM OR ARGON ALSO FLOWS THROUGH THE FURNACE.

ON COOLING, NANOTUBES WITH ITS BYPRODUCTS CAN BE COLLECTED.

• CHEMICAL VAPOR DEPOSITION CATALYST IS DEPOSITED ON SUBSTRATE. CARBON SOURCE IS THEN PLACED IN

GAS PHASE IN REACTION CHAMBER. THIS CARBON WILL GET DIFFUSED

TOWARDS SUBSTRATE, WHICH IS COATED WITH CATALYST AND NANOTUBES GROW OVER THIS METAL CATALYST.

ADVANTAGES OF CVD OVER ELECTRIC ARC AND LASER ABLATION METHODS

• OPERATING TEMPERATURE FOR ELECTRIC ARC DISCHARGE METHOD AND LASER ABLATION METHOD IS MORE THAN 1500°C WHEREAS FOR CVD IS AROUND 650°C.

• DUE TO THE SHORT PROCESS TIMES OF ELECTRIC ARC DISCHARGE METHOD AND LASER ABLATION METHOD, ONLY SYNTHESIS OF THE SHORT NANOTUBES IS POSSIBLE.

• AMOUNT OF PURIFICATION NEEDED FOR ELECTRIC ARC DISCHARGE METHOD AND LASER ABLATION METHOD IS VERY HIGH UNLIKE CHEMICAL VAPOR DEPOSITION

CONVENTIONAL METHOD AND LIMITATIONS

a)CALORIMETRIC INDICATORSb)METAL-OXIDE AND CATALYTIC METAL

DETECTORSC) OPTICAL GAS SENSORSD) ELECTROCHEMICAL SENSORS

SCHEMATIC OF SINGLE WALL CARBON NANO-TUBE GAS SENSING SYSTEM

SENSOR RESPONSE

Block Diagram

REFERENCES• 1. “SENSITIVITY CONTROL FOR NANOTUBE SENSORS” US 6894359 B2 • 2. U.S. PATENT APPLICATION NO.60/748,834 “NANO-ELECTRONICS SENSORS HAVING SUBSTRATES WITH PRE-

PATTERNED ELECTRODES, AND ENVIRONMENTAL AMMONIA CONTROL SYSTEM ” • 3. NO. 11/390,493 LED MAR. 27, 2006 (PUBLISHED 2006- ) ENTITLED “NANO-ELECTRONIC MEASUREMENT SYSTEM

FOR PHYSIOLOGIC GASES, AND IMPROVED NANO-SENSOR FOR CARBON DIOXIDE”. • 4)ROBUST FABRICATION OF SELECTIVE AND REVERSIBLE POLYMER COATED CARBON NANOTUBE-BASED GAS

SENSORS, CHRISTOPHER R. FIELD, JUNGHOON YEOM, AMIN SALEHI-KHOJIN, RICHARD I. MASEL. RECEIVED 19 FEBRUARY 2010, REVISED 27 APRIL 2010, ACCEPTED 12 MAY 2010, AVAILABLE ONLINE 19 MAY 2010.

• 5)LARGE-SCALE INTEGRATED CARBON NANOTUBE GAS SENSORS JOONDONG KIM NANO-MECHANICAL SYSTEMS RESEARCH CENTER, KOREA INSTITUTE OF MACHINERY AND MATERIALS (KIMM), RECEIVED 16 OCTOBER 2011; REVISED 7 MARCH 2012; ACCEPTED 20 MARCH 2012.

• 6) PATTERNING OF CARBON NANOTUBES BY MATERIAL ASSISTED LASER ABLATION PROCESS JUNGHUN CHAE AND KANTI JAIN, FELLOW, IEEE

• 7) FABRICATION AND CHARACTERIZATION OF CARBON NANOTUBES FOR BIOMEDICAL APPLICATIONS BY ZHIYANG RONG

• 8) CARBON NANOTUBES AND GRAPHENE-BASED CHEMICAL SENSORS ABHA MISRA*DEPARTMENT OF INSTRUMENTATION AND APPLIED PHYSICS, INDIAN INSTITUTE OF SCIENCE, BANGALORE 560012, INDIA