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Miniature Distributed Detector Arrays Mounted on a Biological Sensor Platform

We propose a novel methodology to conduct nuclear detection using roach-based sensors. This approach opens new areas of investigation and development in sensing technology and robust intelligence. This will advance the frontiers for disciplines in nuclear detection, cyborg insects, sensing and sensor systems, hybrid robots, and artificial intelligence. Our approach can also be used as monitoring the climate, pollution and presence of overt chemicals. Related applications include search and rescue activities, environmental monitoring, and counterintelligence.

Roaches, especially American cockroaches (Periplaneta americana), are a perfect platform for this project since this is a very common insect, suitable to found throughout the world's populated areas. Even though American roaches prefer to be hidden, they are always associated with humans. Even though the presence of roaches can arouse disgust among some people, it will not necessarily arouse suspicion. Roaches typically live for more than a year after reaching adulthood and they unusually tolerant to noxious environments. Roaches have a somehow large specific payload capacity compared to other insects. A particular advantage of the long life span of the American roaches could even allow us early adult surgery in case that some insect hardware interfaces are needed throughout the platform lifetime.

We will design and develop small sensors for radiation detection that can be implemented on the roach platform. For simplicity we will concentrate first on ion chamber detectors which will allow for gross gamma ray and neutron radiation signals. In outlying years we will develop gamma ray spectroscopy detectors based on CdZnTe detectors and will consider the implementation of solid-state neutron detector systems. Ion chambers are one of the simplest and oldest radiation sensors. These sensors detect ionizing radiation in a chamber filled with air and subject to an electric field. When ionizing radiation interacts in the chamber, charge is produced in the air, and then collected at the anode through the electric field. Ion chambers have the advantage of robustness, simplicity, efficiency, and cost-effectiveness when compared to other radiation detection sensors. These sensors however do not have any ability to discriminate radiation types or to help eliminate background sources. However, when implemented in a distributed detector array (as will be present when the sensors are installed on the roaches), the ion chambers can be used to search for radiation sources. Another advantage of beginning with the development and implementation of ion chamber sensors is that this will reduce risk in the development process. The simplicity of this sensor design provides for a low-risk first year product which can lead to additional successes with next generation sensor systems.

Following the success of designing and implementing the ion chamber detector systems, we will design and develop gamma ray spectroscopy systems based on semiconductor detector systems (specifically, CdZnTe detectors). These detector systems will allow for measurement of both the energy and intensity of gamma ray radiation in the presence of the roaches. Using the energy discrimination capabilities of these sensors will allow for unique identification of the radioisotopes present in the environment. The design and implementation of these sensor systems will be more involved than that for the ion chamber detectors and will require significantly more signal processing. Also, the detector efficiencies and costs are much higher. Thus, it is envisioned that in operation the ion chamber roaches will be used for gross survey of an area to localize sources of radiation, then the CdZnTe roaches will be moved toward that source of radiation and the signals measured by those sensors will be used to characterize the radionuclides in the localized area. The use of these detectors as a distributed sensor array will allow for accurate location determination and identification of any nuclear or radiological material in the vicinity. We have been actively involved in the development of portable radiation sensor systems and methods for analyzing signatures for distributed radiation sensor arrays for several years.29,30,31,32 However, this project represents a significant advance in detector system miniaturization and will require efficient use of sensor design, power consumption, and signal analysis.

For completeness, we will also consider (from simulations only) the possibility of using neutron sensors on the roaches. While small neutron sensors are also possible, the energy discrimination capability of the gamma ray sensor will likely provide more information to be used in analysis of any potential radiation field and discriminating this field from background. The interest in developing neutron sensors would only be due to the possible use of coincidence counting to detect nuclear materials. Coincidence counting is an advanced detection technique that utilizes detection of coincident neutron sources (which are essentially limited to only nuclear materials) via simultaneous detection of events in multiple sensors. This advances may prove useful in future systems but is likely outside the scope of this work.

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The Cockroach Backpack
The Cockroach Backpack

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