1. TO INDICATE TOXIC LEVEL OF
AMMONIA USING CARBON-NANOTUBE
SENSORS
BY:
AAKASH MHANKALE-803000470
DEEKSHA SIVAKUMER-893513473
PRIYANKA NARASIMHA REDDY-
803019033
ROHAN MEHTA-802954974

2. 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.

3. 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

4. APPLICATIONS AREAS OF AMMONIA SENSORS
• ENVIRONMENTAL GAS ANALYSIS
• AUTOMOTIVE INDUSTRY
• CHEMICAL INDUSTRY
• MEDICAL APPLICATIONS FOR AMMONIA SENSORS

5. TYPES OF RESPIRATORS USED IN
INDUSTRIES
• DISPOSABLE PARTICULATE
RESPIRATORS
• CHEMICAL CARTRIDGE
RESPIRATORS
• POWERED AIR-PURIFYING
RESPIRATORS
• SCBA OR SELF-CONTAINED
BREATHING APPARATUS
UNITS

6. 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 SAFETYAND 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 SAFETYAND HEALTH
(NIOSH) ARE SOME FEDERALAGENCIES 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.

7. 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.

8. BASIC CRITERIA FOR GOOD AND EFFICIENT
GAS SENSING SYSTEMS
• HIGH SENSITIVITYAND SELECTIVITY.
• FAST RESPONSE TIME AND RECOVERY TIME.
• LOW ANALYST CONSUMPTION.
• LOW OPERATING TEMPERATURE AND TEMPERATURE INDEPENDENCE.
• STABILITY IN PERFORMANCES.

9. CARBON NANO TUBES
THERE 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.

10. 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

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

12. 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.

13. • 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.

14. • 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.

15. 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

16. CONVENTIONAL METHOD AND
LIMITATIONS
a)CALORIMETRIC INDICATORS
b)METAL-OXIDE AND CATALYTIC METAL
DETECTORS
C) OPTICAL GAS SENSORS
D) ELECTROCHEMICAL SENSORS

18. SCHEMATIC OF SINGLE WALL CARBON NANO-
TUBE GAS SENSING SYSTEM

19. SENSOR RESPONSE

20. Block Diagram

25. 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