Patent Description:
Rodent learning ability has been known for many years.

Animals including dogs and rats are conventionally used to detect odors of interest, e.g. as described in <CIT> Two approaches are used; the first has the animal search an area for a specific scent ("free-running" approach) whereas the second -- the REST (remote explosive scent tracing) approach -- collects odors e.g. by suction onto filters, and then, a group of plural filters is simultaneously presented to the dog who sniffs each of the plural filters to determine if the target odor is present or not. In this field, <CIT> discloses a portable scent transfer device for collecting and presenting various scents, wherein collected scents may be presented to a trained dog to sniff the collected scent, e.g. to find missing persons.

If the target odor is present the dog makes a response which the human handler interprets as indicative of presence of a target odor. REST allows a dog to be tested in a climate controlled location, even when the samples are collected in extreme climates. Also, suctioning the odor out of, say, a pallet, vehicle e.g. truck or container, e.g. via a filter, permits the dog to determine if explosives (say) are present, e.g. by sniffing the filter, without having to unload and separate the containers to allow a free-running dog to search. Thus, the REST approach provides considerable savings.

Patent <CIT>describes a method and apparatus for use in detecting faint olfactory filters.

Use of a single-hole enclosure for early training of an animal, i.e. presenting just one filter to the animal at a time during a learning phase, is described e.g. in <NPL>.

<CIT> discloses a system for presenting a rat with an odor of a target substance or a distractor substance, wherein the rats are trained to recognize the substances.

However, <CIT> does not disclose a real-time selection criterion according to which the rats may be rated in terms of their performance with regard to their training. Once an animal is trained, olfactory detection of unknown samples is conventionally performed using enclosures with plural holders via which plural unknown filter samples are presented simultaneously.

"Filter" is used throughout the specification and claims to mean a device or material for trapping vapor and dust particles. An example of this is seen in <CIT>.

Certain embodiments of the present invention seek to provide an improved system, and/or method and/or computer program product for animal-based olfactory detection.

Certain embodiments of the present invention seek to provide processing circuitry comprising at least one processor in communication with at least one memory, with instructions stored in such memory executed by the processor to provide functionalities which are described herein in detail.

In accordance with an embodiment of the invention, there is provided a method for animal-based olfactory detection of one or more target substances in a sequence of filters the method including:.

The method further comprises the steps of sensing by a sensor an event in which within a predetermined window of time after presentation of a sample, the rat, having been trained to be responsive to the detection of a target substance inserts its head into a positive reinforcement dispenser within the predetermined window of time;
on a computer, calculating and displaying, in real-time, a sensitivity and selectivity of the rat and of an integrated response to the filters, wherein the sensitivity is a percentage of hits on positive filters and the selectivity is a percentage of correct rejects on negative filters of the rat.

Furthermore, the structural element has a conveyor external to the one or more enclosures and the method includes moving move one sample at a time into a predetermined extent of proximity with the aperture.

Furthermore, the one or more enclosures includes at least first and second enclosures and also includes a structural element configured to initially provide a predetermined extent of proximity between plural olfactory samples mounted on the structural element and the aperture in the first enclosure, and to subsequently provide the predetermined extent of proximity between plural olfactory samples mounted on the structural element and the aperture in the second enclosure, wherein proximity is created between samples and each aperture, one sample at a time.

Additionally, the step of sensing an event includes sensing an event automatically, by one of the following list:.

Furthermore, each filter bears a machine-readable code, the method including detecting the machine-readable code and deriving the filter type, and wherein automatic determination of filter type includes using a video camera positioned to capture the machine-readable code and using one or more pre-stored tables to translate the machine-readable code into filter type.

In accordance with a further embodiment of the invention, there is provided a system for animal-based olfactory detection of one or more target substances in a sequence of filters, the system including:.

The system further comprises sensors configured to sense an event in which within a predetermined window of time after presentation of a sample, each rat, having been trained to be responsive to the detection of a target substance inserts its head into a positive reinforcement dispenser within the predetermined window of time;
a computer configured to calculate and display, in real-time, a sensitivity and selectivity of the rat and of an integrated response to the filters, wherein the sensitivity is a percentage of hits on positive filters and the selectivity is a percentage of correct rejects on negative filters of the rat.

Additionally, the structural element has a conveyor external to each enclosure, for moving move one sample at a time into a predetermined extent of proximity with the aperture.

Additionally, the one or more enclosures include at least first and second enclosures and also including a structural element configured to initially provide a predetermined extent of proximity between plural olfactory samples mounted on the structural element and the aperture in the first enclosure, and to subsequently provide the predetermined extent of proximity between plural olfactory samples mounted on the structural element and the aperture in the second enclosure, wherein proximity is created between samples and each the aperture, one sample at a time.

The sensors are configured to automatically sense an event in which within a predetermined window of time after presentation of a sample, the animal, having been trained to do so responsive to its detection of the one or more target substances removes its nose from the aperture and inserts its head into the positive reinforcement dispenser within a predetermined window of time.

Additionally, the sensors are selected from the following list:.

Furthermore, each the filter bears a visual indication, and the system includes the step of detecting each the visual indication by photo-sensors.

Additionally, each the filter bears a machine-readable code, and the system includes apparatus for video capture of the machine-readable code and translation of the machine-readable code into filter type.

Also provided, excluding signals, is a computer program comprising computer program code means for performing any of the methods shown and described herein when the program is run on at least one computer; and a computer program product, comprising a typically non-transitory computer-usable or -readable medium e.g. non-transitory computer -usable or - readable storage medium, typically tangible, having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement any or all of the methods shown and described herein. The operations in accordance with the teachings herein may be performed by at least one computer specially constructed for the desired purposes or general purpose computer specially configured for the desired purpose by at least one computer program stored in a typically non-transitory computer readable storage medium. The term "non-transitory" is used herein to exclude transitory, propagating signals or waves, but to otherwise include any volatile or non-volatile computer memory technology suitable to the application.

Any suitable processor/s, display and input means may be used to process, display e.g. on a computer screen or other computer output device, store, and accept information such as information used by or generated by any of the methods and apparatus shown and described herein; the above processor/s, display and input means including computer programs, in accordance with some or all of the embodiments of the present invention. Any or all functionalities of the invention shown and described herein, such as but not limited to operations within flowcharts, may be performed by any one or more of: at least one conventional personal computer processor, workstation or other programmable device or computer or electronic computing device or processor, either general-purpose or specifically constructed, used for processing; a computer display screen and/or printer and/or speaker for displaying; machine-readable memory such as optical disks, CDROMs, DVDs, BluRays, magnetic-optical discs or other discs; RAMs, ROMs, EPROMs, EEPROMs, magnetic or optical or other cards, for storing, and keyboard or mouse for accepting. Modules shown and described herein may include any one or combination or plurality of: a server, a data processor, a memory/computer storage, a communication interface, a computer program stored in memory/computer storage.

The term "process" as used above is intended to include any type of computation or manipulation or transformation of data represented as physical, e.g. electronic, phenomena which may occur or reside e.g. within registers and /or memories of at least one computer or processor. The term processor includes a single processing unit or a plurality of distributed or remote such units.

The above devices may communicate via any conventional wired or wireless digital communication means, e.g. via a wired or cellular telephone network or a computer network such as the Internet.

The apparatus of the present invention may include, according to certain embodiments of the invention, machine readable memory containing or otherwise storing a program of instructions which, when executed by the machine, implements some or all of the apparatus, methods, features and functionalities of the invention shown and described herein. Alternatively, or in addition, the apparatus of the present invention may include, according to certain embodiments of the invention, a program as above which may be written in any conventional programming language, and optionally a machine for executing the program such as but not limited to a general purpose computer which may optionally be configured or activated in accordance with the teachings of the present invention. Any of the teachings incorporated herein may wherever suitable operate on signals representative of physical objects or substances.

The embodiments referred to above, and other embodiments, are described in detail in the next section.

Any trademark occurring in the text or drawings is the property of its owner and occurs herein merely to explain or illustrate one example of how an embodiment of the invention may be implemented.

Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions, utilizing terms such as, "processing", "computing", "estimating", "selecting", "ranking", "grading", "calculating", "determining", "generating", "reassessing", "classifying", "generating", "producing", "stereo-matching", "registering", "detecting", "associating", "superimposing", "obtaining" or the like, refer to the action and/or processes of at least one computer/s or computing system/s, or processor/s or similar electronic computing device/s, that manipulate and/or transform data represented as physical, such as electronic, quantities within the computing system's registers and/or memories, into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices. The term "computer" should be broadly construed to cover any kind of electronic device with data processing capabilities, including, by way of non-limiting example, personal computers, servers, embedded cores, computing system, communication devices, processors (e.g. digital signal processor (DSP), microcontrollers, field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.) and other electronic computing devices.

Elements separately listed herein need not be distinct components and alternatively may be the same structure. A statement that an element or feature may exist is intended to include (a) embodiments in which the element or feature exists; (b) embodiments in which the element or feature does not exist; and (c) embodiments in which the element or feature exist selectably e.g. a user may configure or select whether the element or feature does or does not exist.

Any suitable processor/s may be employed to compute or generate information as described herein and/or to perform functionalities described herein and/or to implement any engine, interface or other system described herein. Any suitable computerized data storage e.g. computer memory may be used to store information received by or generated by the systems shown and described herein. Functionalities shown and described herein may be divided between a server computer and a plurality of client computers. These or any other computerized components shown and described herein may communicate between themselves via a suitable computer network.

The scale used to illustrate various elements in the drawings is merely exemplary and/or appropriate for clarity of presentation and is not intended to be limiting.

Methods and systems included in the scope of the present invention may include some (e.g. any suitable subset) or all of the functional blocks shown in the specifically illustrated implementations by way of example, in any suitable order e.g. as shown.

Each functionality or method herein may be implemented in software, firmware, hardware or any combination thereof.

Any hardware component mentioned herein may in fact include either one or more hardware devices e.g. chips, which may be co-located or remote from one another.

Any method described herein is intended to include within the scope of the embodiments of the present invention also any software or computer program performing some or all of the method's operations, including a mobile application, platform or operating system e.g. as stored in a medium, as well as combining the computer program with a hardware device to perform some or all of the operations of the method.

<FIG> illustrate an example system for REST odor detection using an animal such as a rodent or rat. For example, a laboratory rat of an outbred strain e.g. a (Sprague-Dawley rat) may be employed. If water or food are used as a reward, the animal may be water or food deprived for several hours. Using a small amount of water or food as a reinforcer allows rats to efficiently make positive detections of many known samples e.g. filters. Play can also be used for reinforcement e.g. for canines, but is more time consuming. Any other suitable reward may be employed such as food or a pleasing auditory or visual or tactile experience.

A test chamber or enclosure <NUM> (<FIG>) is used to house the rat who can inspect each filter or other olfactory sample, typically one by one, and report if a target odor is present, having been trained to do so. If the odor is present and the rat reports that it is present, the rat will receive a reward e.g. a small amount of water.

Air sampling to generate odor-bearing filters may proceed in accordance with any of the teachings of any of the following Israel patent documents:.

More generally, olfactory filters e.g. trucks or cargo or containers which are suspected of containing explosives and/or must be searched pursuant to government regulations may be sampled in any desired manner -- such as but not limited to filters through which adjacent air containing explosive molecules, has been forced or dust which has been vacuumed from the trucks or cargo or containers.

Photoreceptors may be provided at a suitable location e.g. underneath the floor of the cage or enclosure housing the animal. Alternatively, a camera or bar code reader or QR code reader may be provided in conjunction with suitable visual indication/s on the sample/s e.g. filter/s so as to classify each filter e.g. as known positive, known negative or unknown, and/or type of substance/explosive and/or ID of truck or pallet or container or other suspect substrate from which the sample was taken.

A sled <NUM> (<FIG>) may be used for placement of plural filters which contain odor collected, e.g. by suction, from pallets, vehicles, or containers. The sled is translated by a conveyor <NUM> (<FIG>) past a suitable odor presentation point in the enclosure, typically so as to present one sample at a time to the animal. As shown in <FIG>, a local or remote computer <NUM> is provided which is typically in direct or networked data communication, wired or wireless, with the enclosure of <FIG> and/or the sled <NUM> and conveyor <NUM>, e.g. as described herein in detail, and records the responses to the filters and provides a reward for positive responses (hits) on known filters (filters known to possess the target odor). Typically, even during testing, known positive samples are provided as well as unknown samples e.g. in accordance with a random schedule with a known ratio of known positives vs. unknown. Typically, a reward is provided only for the known positives and not for the unknowns. The ratio of known positives vs. unknown is selected to be high enough to maintain the animal's learned response. If for example, a positive filter is included each (say) <NUM> filters, literally or on average, the animal remains motivated to inspect unknown samples even though these are not rewarded.

The test chamber <NUM> is formed of any suitable structural material such as, say, Perspex, and may be of any suitable size; typically 30x30x20 cm is sufficient. Below the test chamber a lower section or basement <NUM> may be provided some or all of which may serve as a tunnel <NUM> for insertion and translation of the sled <NUM>. The basement <NUM> may be equipped with electronic photosensors (not shown). The front part of the lower chamber may serve as the tunnel for insertion and translation of the sled, below a sample presenting structure e.g. an aperture <NUM> of suitable diameter e.g. <NUM> (in the right front section of the chamber in the illustrated embodiment). The aperture <NUM> is typically large enough to accommodate the animal's snout but not its entire body. This olfactory sample presentation point e.g. aperture is typically close to the reward presentation point if it is desired that the animal spend as little time as possible scampering back and forth between the two.

The test chamber <NUM> typically has a door (not shown) for insertion and removal of the rat, a ventilating fan <NUM>, a chamber light e.g. LED <NUM> and (on the right wall in the illustrated embodiment) an opening <NUM> for providing reward/reinforcement e.g. using any conventional reinforcement delivery system such as the commercial unit produced by Coulbourn Instruments. A sonalert/ piezoelectric tone generator may be provided to generate feedback for incorrect responses.

The floor121, side <NUM>, and back walls <NUM> may be opaque e.g. black whereas the front wall <NUM> may be transparent to enable the animal to be observed.

Referring now to <FIG>, in the illustrated embodiment, the sled <NUM> includes N e.g. eight or <NUM> or <NUM> compartments referenced <NUM>, for the insertion of N filters. Between the filter compartments is a raised barrier <NUM> which both inhibits movement of the odor between filters and serves as a stop for the movement of the sled between filters. The sled <NUM> may translate along a runway (not shown) formed of a material which allows smooth movement of the sled e.g. Perspex.

More generally, the sled <NUM> or other structure may have any suitable configuration which supports and presents sequentially, plural olfactory samples to the aperture <NUM> in the enclosure <NUM>, without allowing odor in one sample to contaminate the other.

Typically, three types of filters are used in the REST paradigm: a known positive (known to have an explosive odor), known negative filter (known to lack an explosive odor) and unknown or `probe', used e.g. for testing and/or operations. The unknown or probe filter is of unknown nature, i.e. it is not known whether or not it contains an explosive odor. The computer <NUM> of <FIG> is typically programmed to receive an input which identifies the type of filter currently being presented and to adjust the consequences of the rat's response according to a suitable preprogrammed schedule e.g. a reinforcement reward for some, most or all known positives to which the animal responds correctly, but not for unknowns or probes or for known negatives.

Any suitable implementation may be employed to provide a filter-type identifying input to the computer, e.g. by suitably differentially marking the various filter types. For example, in the illustrated embodiment, the back wall of the sled has two <NUM> diameter holes <NUM> formed exactly opposite the filter compartments <NUM>. The filter status or type is then determined by two photosensors (not shown) in the lower chamber <NUM> focused on the two sled wall holes <NUM> respectively. Then, each type of filter is differentially marked e.g. positive filters have a black band on the upper part of the filter which can be detected by the upper photosensor. Negative filters have the same band on the lower part of the filter which can be detected by the lower photosensor. Thus, the differential activation of the photosensors allow the computer <NUM> to identify the filter as positive or negative, whereas if neither photosensors is activated, the filter is unknown (if unknown filters have no black bands). Alternatively, any other visual marking of filter types may be employed, and other types of readers may be employed e.g. the photosensors may be replaced with, say, a QR code reader or Bar Code reader. In this case, the holes <NUM> (<FIG>) must be sufficiently large to enable the reader to read the QR code of barcode. In one embodiment, the back wall of sled <NUM> may be removed entirely.

The computer <NUM> also records the animal's responses as sensed. For example, if a sample is a known positive filter and the rat responds positively, this is recorded as a "hit" (and the rat always or P% of the time, is given a water reward). If the filter is a known positive and the rat fails to respond, the system registers the response as a "miss". If the filter is a known negative filter and the rat responds accordingly, the system registers the response as a "correct reject. " If the rat responds inappropriately to the known negative filter the response is recorded as a "false positive" response. If the rat responds to an unknown filter as if it were positive, the system records the response as a YES. If the rat responds as if the filter is negative, they system records the response as a NO.

Any suitable sensor may be used to sense the animal's actions. For example, as shown in <FIG>, a photosensor may be positioned to sense that the rat has inserted it nose into the aperture <NUM> via which the samples are presented. Also, a photosensor may be positioned to detect that the rat has inserted its head into the water delivery device <NUM>. The computer <NUM> typically stores time-stamped indications of these sensor outputs. Thus, the computer <NUM> can determine the amount of time which elapses from when the rat smells the sample to when the rat interacts with the reward delivery device.

Example: Operation of the system of <FIG> may proceed as follows: A rat is placed in the chamber <NUM> of <FIG>. Positive, negative and unknown filters are loaded manually or automatically onto the sled <NUM> of <FIG>, into each of the holes <NUM>. The sequence of the filters is determined randomly and is also a function of the number of unknown filters that have to be checked. The sled <NUM> is moved manually or automatically so that the first filter is under the hole <NUM> in the floor <NUM> of chamber <NUM>.

According to certain embodiments, once the filter is positioned, the house light <NUM> turns on providing a signal to the rat to begin checking the filter. If the animal fails to check the sample e.g. filter within a predetermined window of time of (say) one minute, the shift for that animal is terminated e.g. the animal is removed from the enclosure <NUM> and replaced by another animal. Any suitable sensor e.g. as described herein, may be used to detect that the animal has begun checking the sample e.g. has placed his head in the aperture. If the rat does begin checking e.g. inserts it nose into the aperture <NUM> above the filter, the system then waits for the animal to remove its nose and make a response. If the filter is positive the rat has a predetermined time window e.g. less than one second e.g. <NUM> or <NUM> seconds or <NUM> seconds to generate its learned response to presence of target odor/s e.g. to put its head into the reward delivery device aperture <NUM>. A suitable time-window duration may be pre-selected by testing for an optimal duration which yields good detections rates e.g. low rates of type <NUM> and <NUM> detection errors. If the rat put its head into the water device aperture <NUM> (or more generally is detected to have approached the reward delivery device), the photocell is activated and responsively, the computer commands the water delivery system to deliver the water reward. If, after removal of its nose from the aperture below which a known negative filter has been presented the rat does not go to the water, this is recorded as a "correct reject" and the light is turned off. The rat only gets rewarded for correct positive responses. Optionally, if the rat puts its head in the water delivery device aperture <NUM> before inserting its nose into the filter hole <NUM> a short beep is sounded. Likewise, a beep may be sounded when the rat makes a false positive response. In the case of unknown filters there is no reward and no beep contingent on the response. Once the rat has made a response the house light <NUM> is switched off and the rat waits for the next filter. It is appreciated that all or any subset of the occurrences above may be provided, according to various embodiments of the invention.

In a typical display, any of all of the following graphic display elements may be displayed, typically separately on each of <NUM> screens relating to the <NUM> (or plural) animals respectively; it is appreciated that the specific icons stipulated below are merely by way of example:.

Detection outcomes which may include, say:.

In the illustrated example display, any of all of the following graphic display elements are presented in a suitable manner, to summarize the results of both (or plural) animals together; it is appreciated that the specific icons stipulated below are merely by way of example:.

It is appreciated that the example embodiment of <FIG> is designed to accommodate a manual option, inter alia, in which a human operator may advance the sled <NUM> manually to the next filter thereon responsive to an indicator e.g. when a house light <NUM> is switched off. The house light <NUM> is controlled to turn off either after the rat gets reinforced or after <NUM> seconds, if that is the window for the rat to make a positive response. Alternatively, the system may be automated in which case the next filter may be presented right after the animal is detected to have responded or after the time window for the animal response has elapsed. In this case, the sled may be replaced by a conveyor <NUM> more suited for automatic operation.

The computer of <FIG> may more generally include any processor programmed for some or all of the following functionalities, which may also be provided stand-alone as a computer program product:.

In more detail, a processor e.g. the computer of <FIG>, or stand-alone computer program product, may be operative for all or any subset of the following functionalities:.

<FIG> is a simplified flowchart illustration of a method for animal-based olfactory detection of one or more target substances in a sequence of filters. It will be appreciated that included among the various possible results is the possibility that no explosive substance or explosive odor emitting substance is present in the sequence of filters. The method may or may not include all or any subset of the various features of <FIG> and may or may not provide some or all of the software functionalities described above. In the method of <FIG>, some or all of the illustrated operations may be provided, suitably ordered e.g. as follows:.

It is appreciated that normal operation is preceded by animal training which may proceed in accordance with any suitable animal training method for canines, rodents e.g. rats or other. The animal may be trained to recognize any olfactory substance such as but not limited to one or more explosives e.g. one or more of, say, TNT, RDX, PETN, ammonium nitrate, guns and ammo, fireworks, PX64, SEMTEX, EURODYN2000, doramite, EGDN, nitroglycerin, DNT. Typically, the animal if being trained to recognize odors of several olfactory substances e.g. to respond positively to any of several odors, is first trained on a first olfactory substance, then once training has been completed, the animal is trained on the next and the next. It is found that once a RAT (say) has understood the task, it is very easy to introduce new substances e.g. additional explosives. During training, the animal typically is rewarded using the same reward dispenser later used during testing. The animal may be trained to perform any desired, typically automatically recognizable action upon encountering the target odors and not otherwise. For example, the animal may be trained to approach the reward dispenser e.g. to insert its head past a suitable proximity detector or other sensor deployed in front of the reward dispenser.

Typically, plural animals e.g. rodents e.g. rats sequentially inspect the same samples, as shown in <FIG>. If plural e.g. two (in the illustrated embodiment) animals are not in accord regarding an unknown filter, it is typically rerun, disregarded, or otherwise processed. Then, the sensitivity (percentage of hits on positive filters) and selectivity (percentage of correct rejects on negative filters) on the combined record of the two rats are both over <NUM>%.

An advantage of certain embodiments is that the rat inspects each filter before the next filter is presented, in contrast to conventional REST systems in which the animal can skip filters.

Another advantage of certain embodiments is automatic sensing of the animal's response in contrast to conventional REST systems, in which there is reliance on human trainer determination of whether the rat made a response or not. This is costly and also allows the trainer to have a significant influence over the response of the animal.

Still another advantage of certain embodiments is simplicity; in prior art devices is in which rodents are expected to interact with <NUM> or more samples presented via <NUM> or more respective apertures in the enclosure housing the rodent, it is necessary to provide covers to allow covering each aperture after it has been interacted with to encourage the rodent to interact only with "new" apertures, then uncovering the apertures for another batch of <NUM> samples once the <NUM> current samples have finally been smelled by the rodent.

Still another advantage of certain embodiments is that both sensitivity (hits/positives) and selectivity (corrective rejections/negatives i.e. inverse of false alarm rate) for detecting explosives in cargo exceed <NUM>% and even <NUM>% - far in excess of the sensitivity and selectivity characterizing human detection of explosives in cargo.

Yet another advantage of certain embodiments is that olfactory detection includes differentiating between presence and absence of the target substance/s parsimoniously and effectively, by sensing an event in which within a predetermined window of time after presentation of a sample, the animal, having been trained to do so responsive to target substance/s, approaches a reinforcement dispenser e.g. inserts its head into the reinforcement dispenser, rather than, for example, training the animal to remain in contact with positive olfactory samples for at least a predetermined time period and remaining in contact with negative olfactory samples for less than the predetermined time period and then detecting that, or requiring a human attendant to provide a manual input based on that behavior.

The applicability of certain embodiments includes but is not limited to screening of cargo for explosives or narcotics.

It is appreciated that terminology such as "mandatory", "required", "need" and "must" refer to implementation choices made within the context of a particular implementation or application described herewithin for clarity and are not intended to be limiting since in an alternative implantation, the same elements might be defined as not mandatory and not required or might even be eliminated altogether.

The system may if desired be implemented as a web-based system employing software, computers, routers and telecommunications equipment as appropriate.

Claim 1:
A method for rat-based olfactory detection of at least one target substance in a sequence of filters, the method comprising:
providing (<NUM>) at least one enclosure (<NUM>) each housing a rat, the enclosure (<NUM>) including a aperture (<NUM>) via which only a single olfactory sample is presented to the rat at any given time;
with a structural element configured to create a predetermined extent of proximity between plural olfactory samples mounted on the structural element and the aperture (<NUM>), one sample at a time, such as a translating or rotating tray, a sled (<NUM>), a carousel or a conveyor (<NUM>), presenting (<NUM>) samples of the sequence of filters one at a time to the rat via the aperture (<NUM>), thereby facilitating olfactory detection of target substances in the sequence of filters;
by a sensor sensing (<NUM>) an event in which within a predetermined window of time after presentation of a sample, the rat, having been trained to be responsive to the detection of a target substance inserts its head into a positive reinforcement dispenser within the predetermined window of time;
on a computer (<NUM>), calculating and displaying, in real-time, a sensitivity and selectivity of the rat and of an integrated response to the filters, wherein the sensitivity is a percentage of hits on positive filters and the selectivity is a percentage of correct rejects on negative filters of the rat.