HAND-HELD
EXPLOSIVES SENSOR SYSTEM
by
Charles
D. Bosco
Senior
Research Engineer
Systems
Management and
Prepared by
UTCA
The
and the
UTCA Report Number 03306
Technical Report
Documentation Page
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Hand-Held Explosives Sensor System |
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Author Charles D. Bosco |
UTCA Final Report |
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Contract or Grant No. UTCA Identification Number - 03306 |
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Sponsoring Agency Name and Address |
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Type of Report and Period Covered Final Report |
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Abstract One of the most important
problems facing the U.S. Department of Transportation is the detection of
illegal chemicals and explosives entering this country. There are various government agencies
performing detection by means of physical inspections, sophisticated
detection instrumentation and trained sniffing dogs. All of these methods have their
limitations, especially costs. The purpose of this
investigation was to study the feasibility of integrating a variety of
microcantilever sensors into a hand-held sensor system capable of sensing and
identifying illegal explosives. Researchers
at the An extensive literature
search was performed to determine the U.S. Department of Transportations
challenges in detecting contraband explosives. This included a technical evaluation of
present-day detection instrumentation and the capabilities of sniffing
dogs. It was followed by a detailed
study of microcantilever technology and its application to explosives detection. To determine the latest state-of-the-art,
interviews were conducted with a customs inspector, a sniffing dog handler,
and the head of a microcantilever laboratory.
Other sensor technology was investigated to ensure that
microcantilevers are indeed the most appropriate for explosives
detection. The investigation
concluded with a prototype design of a multi-sensor system, and a cost
analysis of fabricating such a system. |
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Key Words Chemical sensors,
microcantilever, explosives, homeland security |
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Distribution Statement |
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Security Class (report) Unclassified |
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Security Class. (Of this page) Unclassified |
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3.0 Explosives
..
10
Introduction
.
10
Taggants
..
12
4.0 Detection Instrumentation
14
5.0 SniffingDogs
18
Capability of Sniffing Dogs
.
.. 18
Accuracy
18
Sensitivity
.
. 19
Comparison With Instrumentation
. 20
Volatility Problems
21
Limitations of Sniffing Dogs
.
. 22
Comparison of Sniffing Dogs to Sensing Instrumentation
. 23
Army Working Dogs
.. 25
6.0 Current Instrumentation
27
7.0 Microcantilever Technology
.
30
Introduction
. 31
Background Technology
. 32
Sensor Detection Methods
.. 33
Physical Properties
..
33
Microcantilever Sensitivity
.
34
Sensitivity
Analysis
.
34
Detection of Explosives
...
37
Advantages of Microcantilevers over Conventional Sensors
..
38
Comparison of Microcantilever Sensors to Sniffing Dogs
..
. 38
Accuracy and Stability
.
. 40
8.0
Prototype of Explosives Sensor Design
..
43
Introduction
..
. 43
Developing the Sensors
.. 43
Designing the Electronics
.
44
Designing the Software
. 44
Designing the Display
45
Designing the Power Supply
.
. 46
Designing the Package
.. 46
Estimated Research and Development Effort
46
Sensor Development
.
. 46
Electronics Development
46
Software Development
.. 46
Development of Package
... 47
Estimate of Final Cost of Sensor System
.
. 47
9.0
Conclusions and Recommendations
.... 48
10.0
References
..
50
List of Tables
Number Page
3-1 Chemical composition of commonly used
explosives
10
3-2 Common major chemicals found in explosives
and explosive mixtures
.. 11
5-1 General comparison between instrumentation
explosive detection devices and
trained detector dogs
. 23
7-1 Comparison of techniques for mercury
analysis
35
7-2 Gravimetric
sensitivity of oscillating acoustic wave devices
36
Number Page
7-1 Different micrometer response modes
33
One of the most important problems facing the U.S. Department of Transportation is the detection of illegal chemicals and explosives entering this country. There are various government agencies performing detection by means of physical inspections, sophisticated detection instrumentation and trained sniffing dogs. The use of inspectors is expensive due to the limited number and the cost of personnel. Instrumentation is very useful, but the more sensitive instruments are very expensive, and therefore, are purchased in limited numbers. Sniffing dogs provide a very good compromise. The handlers provide the human evaluation and decision making while the dogs are very good at detecting trace odors of explosives, drugs, and currency. The problems associated with dogs are that a trained dog is expensive and requires a skilled handler and upkeep. Also, dogs cannot work long hours.
The purpose of this investigation was to study the
feasibility of integrating a variety of microcantilever sensors into a
hand-held sensor system capable of sensing and identifying illegal
explosives. Researchers at the
An
extensive literature search was performed to determine the U.S. Department of
Transportations challenges in detecting contraband explosives. This included a technical evaluation of
present-day detection instrumentation and the capabilities of sniffing
dogs. It was followed by a detailed
study of microcantilever technology and its application to explosives
detection. To determine the latest
state-of-the-art, interviews were conducted with a customs inspector, a sniffing dog
handler, and the head of a microcantilever laboratory. Other sensor technology was investigated to
ensure that microcantilevers are indeed the most appropriate for explosives
detection.
The investigation concluded with a prototype design of a multi-sensor system, and a cost analysis of fabricating such a system.
Section 1.0
Project Objective
One of the most important new scientific accomplishments to emerge recently from sensor research has been the development of microcantilever sensors. This sensor has been demonstrated to have such extreme sensitivity that specialized sensor systems using this technology have the potential to equal or exceed the detection capabilities of sniffing dogs and some of the more sensitive laboratory measuring equipment. The object of this investigation was to determine the feasibility of integrating a variety of microcantilever sensor devices in a hand-held sensor system capable of sensing and identifying trace amounts of explosives. Trained dogs and some specialized portable instrumentation traditionally do this work very well, however, the new microcantilever technology has the potential of replacing sniffing dogs and reducing the size and cost of portable instrumentation. A sensor system based on this technology could enjoy widespread use for U.S. Department of Transportation (USDOT) inspectors.
As part of this investigation, an analysis was made of the projected cost of a hand-held sensor, assuming that one could be built to match or exceed the effectiveness of dogs.
The
approach to this investigation was to accomplish the following tasks:
1. Study the USDOTs challenges
in identifying contraband containing explosives.
2. Study the present technology
used to detect explosives and determine its effectiveness, ease of use, cost,
and upkeep.
3. Evaluate the capability of
sniffing dogs to detect explosives.
4. Evaluate microcantilever
technology.
5. Determine whether a
cost-affordable multi-sensor system can be designed and fabricated.
Introduction
The focus of this investigation is to support the U.S. Department of Transportation in its quest for new technology to improve the detection of contraband explosives. Consequently, it will be useful to briefly describe the problems encountered by USDOT inspectors.
The
Department of Transportation is faced with the overwhelming task of preventing
the transportation of illegal explosives into and throughout the
Contraband consists of many things, including drugs and currency, however this investigation will only be concerned with the detection of explosives or chemicals used in explosives.
Currently, inspections are done using inspectors, detection instrumentation, and sniffing dogs. Each has its strong and weak points, but whenever additional personnel are hired, the expenses increase significantly. Sniffing dogs have been found to be very useful, but they can only detect explosives that are not well sealed. They have other limitations that will be discussed later. Large sophisticated x-ray and other inspection machines are very important in identifying well-sealed explosives embedded in cargo or luggage. These instruments are usually very expensive and even the portable versions are too expensive for wide distribution. These instruments also have their limitations, and which will be discussed later.
Transportation
Inspection Problems
Because of the vast size of the
One of the more recent attempts to address the problem
was to increase the number of inspectors.
At the time of this investigation the airports were hiring 50,000 new
federal screeners to check passengers.
However, only the tiniest percentage of containers, ships, trucks, and
trains that enter the
Because of the costs and the number of inspectors needed, it is impossible to inspect all cargo before it enters the country, when it enters the country, and as it travels throughout the country. Even if it were possible, the delays in delivery would be intolerable. Therefore, an efficient process must be established whereby the USDOT can have a reasonable level of confidence that contraband has not passed through the inspection system. There are major obstacles to this process:
a. High cost of employing a
large number of inspectors.
b. High cost of purchasing and
maintaining sophisticated inspection equipment.
c. Long delays in delivery due
to involved inspection techniques
d. Delays due to false positive signals from measuring equipment
Added to the above problems are the costs associated with training inspectors in the use of the new measuring equipment, and in the case of sniffing dogs, the cost of purchasing and maintaining them. The benefits and disadvantages of using sniffing dogs will be discussed in a later section.
As
can be seen from the above, the major obstacle is cost. As in all finances, costs are managed in two
ways, i.e., the elimination of waste or the increase in revenue. Elimination of waste is always desired, but
because of the seriousness and scope of the problem, we can expect revenues to
increase. The American public realizes
that there are going to be significant costs associated with the protection of
this country. However, even with large
increases in funding, the problems will not be solved. While every single piece of cargo entering
the country could theoretically be inspected, all trade would essentially
stop. Given all this, then what is the
answer?
The
answer is to increase funding significantly for new technology to develop
small, portable, non-intrusive, sensitive, low-cost inspection
instrumentation. This would be a major
undertaking, but the benefits would be worth it. It would allow effective inspections without
significantly affecting the free flow of commerce.
There are over 40 departments of the
Methods of Detection
Aside from physical inspection by government agents, inspections are done using fixed instrumentation, portable instrumentation, and sniffing dogs. Depending on the particular situation, one or more of these techniques are used. When possible, a pre-screening analysis is used to determine cargo more likely to contain contraband.