Method and system for capturing and monitoring a physiological parameter and movement within an area of at least one person

A method for capturing and monitoring at least one physiological parameter and movement within an area of at least one person are disclosed. The area is divided into cells having respective location identifiers. Each person is provided with a respective device for measuring at least one physiological parameter of the person. The physiological parameter is indicative of whether the person has a physical condition. Each device has a device identifier. The device is used to at least intermittently measure a physiological parameter of the person using the respective device to obtain a physiological parameter reading for each measurement. The physiological parameter reading is associated with the respective device identifier of the device by which, the respective location identifier of the cell in which, and a time at which the physiological parameter reading is obtained. The associated information is stored at a remote location. A system and a physiological parameter device are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is filed under the provisions of 35 U.S.C. §371 and claims benefit of the priority of International Patent Application No. PCT/SG2003/000171 filed Jul. 17, 2003. The disclosure of said International Patent Application is hereby incorporated herein by reference, in its entirety, for all purposes.

BACKGROUND

This invention relates to a method and a system of tracking movement of a group of people in an area so that when a person in the group is detected to have a physical condition, the person may be located.

The severe acute respiratory syndrome (SARS) is an infectious disease. People who are suspected of having contracted SARS needs to be urgently identified, located and isolated to prevent the spreading of the disease to other people. One of the symptoms of SARS is fever. Consequently, it has become important for monitoring the body temperature of people to determine if they run a temperature, i.e. they have a fever.

Typically, people visiting a building such as an office building or a hospital are required to have their body temperatures taken at the entrance of the building. If the body temperature of a particular person is found to be above a pre-determined threshold, the person may be barred from entering the building, and may be asked instead to consult a doctor. Such a one-time measurement of body temperature may not be ideal.

For example, a person may have a normal body temperature when entering the building. However, the person may subsequently develop a fever after entering the building. And if the person has contracted the SARS virus and remains in the building for hours, he may potentially infect the other people in the building by passing the virus to them. Such a situation may result in a large cluster of SARS infected people and thus poses a serious health threat.

Another reason why a one-time measurement of body temperature is not ideal is because not everyone has the exact same temperature. The normal body temperature of a person varies depending on age, gender, recent activity, food and fluid consumption, time of day, etc., and for women, the stage of a menstrual cycle. The body temperature of a person at a particular time also varies when taken from different parts of the body. A normal body temperature can range from 36.5° C. to 37.2° C. However, a threshold of 37.8° C. is often used for deciding if a person has fever. The use of such a fixed threshold is not ideal because about 5% of the population is known to have a body temperature that falls outside the normal range. Using the single fixed threshold to gauge if a person has fever will cause those having a body temperature higher than that in the range to be wrongly diagnosed to have fever, thereby causing them unnecessary inconvenience and distress. What may be worse is that using such a fixed threshold may not be able to detect fever in people with a normal temperature lower than that in the range. In other words, real cases of fever may not be detectable.

SUMMARY

According to an aspect of the invention, there is provided a method of capturing and monitoring at least one physiological parameter and movement within an area of at least one person. The method includes dividing the area into cells having respective location identifiers and providing each person with a respective device for measuring at least one physiological parameter of each person. The physiological parameter is indicative of whether the person has a physical condition. Each device has a device identifier. The method further includes at least intermittently measuring a physiological parameter of the at least one person using the respective device to obtain a physiological parameter reading for each measurement. The method also includes associating each of at least a selected number of physiological parameter readings with the respective device identifier of the device by which, and the respective location identifier of the cell in which, a time at which the physiological parameter reading is obtained. The method further includes storing the associated physiological parameter reading, device identifier, location identifier and time.

The monitoring may be carried out from a remote location. The method may then include transmitting the associated physiological parameter reading, device identifier, location identifier and time to the remote location prior to storing them thereat.

According to one embodiment, dividing an area into cells involves a deployment of access stations at different locations in a building. Each of the access stations has a respective station identifier that serves as a location identifier. When the device obtains a physiological parameter reading, the device transmits the reading along with the respective device identifier. If the device is within a cell, the access station of the cell is able to receive the reading and device identifier and associate them with the respective station identifier. The access station subsequently transmits the associated reading, device identifier, station identifier to a remote control unit for storage thereon. The remote control unit further associates a time with the reading, device identifier and station identifier received from the access station. The time may also include a date. This embodiment of the invention will be described in detail later.

The method may further include comparing the physiological parameter reading with a first predetermined physiological parameter threshold value to determine if the person is wearing the device properly. In such a case, the method may further include identifying and locating the person using the device identifier and the location identifier associated with the physiological parameter reading if the person is determined not to be wearing the device properly.

The method may also include comparing the physiological parameter reading with a second predetermined physiological parameter threshold value to determine if the person has a physical condition. In such a case, the method further includes identifying and locating the at least one person using the device identifier and the location identifier associated with the physiological parameter reading if the person is determined to have the physical condition. The second predetermined physiological parameter threshold value may be predetermined individually.

The method may include adjusting the physiological parameter reading by a physiological parameter correction factor that is individually determined for the at least one person prior to comparing the adjusted physiological parameter reading with the first or the second predetermined physiological parameter threshold value.

The method may further include matching a time and location identifier associated with at least one physiological parameter reading taken from a respective device of at least one other person with those of the identified and located person and identifying the at least one other person to have been in physical proximity of the identified and located person if there is a match.

According to another aspect of the invention, there is provided a system for implementing the method according to the above described embodiment. The system includes a remote control unit and two or more access stations provided in a spatial arrangement within the area. Such an arrangement thereby divides the area into respective cells. Each access station has a respective station identifier, is being connected to the control unit and is adapted to receive a physiological parameter reading and a respective device identifier from at least one physiological parameter measuring device attached to a first person. The access station transmits the received physiological parameter reading and the device identifier along with its station identifier to the control unit. The associated information and a time at which the physiological parameter reading is obtained by the device is stored in a first record at the remote control unit.

The control unit may be adapted to compare the physiological parameter reading with a first predetermined physiological parameter threshold value to determine if the first person is wearing the device properly. The control unit may further be adapted to provide information corresponding to the device identifier and the location identifier associated with the physiological parameter reading for identifying and locating the first person if the first person is determined not to be wearing the device properly.

The control unit may also be adapted to compare the physiological parameter reading with a second predetermined threshold value to determine if the first person has a physical condition. The control unit may be further adapted to provide information corresponding to the device identifier and the location identifier associated with the physiological parameter reading for identifying and locating the first person if the first person is to have the physical condition. The second predetermined physiological parameter threshold may be predetermined individually for the first person.

The control unit may be adapted to match a time and location identifier of at least another record obtained from another respective device of at least one other person with those in the first record and to identify the other person to have been in physical proximity of the first person if there is a match.

The physiological parameter reading may be adjusted to include a physiological parameter correction factor that is individually determined for the first person prior to comparing the adjusted physiological parameter reading with either the first or second physiological parameter threshold value.

The control unit may be adapted to generate an alert message if the first person is determined either not to be wearing the device properly or to have the physical condition. The alert message includes information corresponding to the station identifier and the device identifier. The alert message may be sent to a predetermined recipient via a communication network to which the control unit is connectable. The communication network may be a public communication network.

The control unit may be further adapted to instruct the device to transmit its device identifier and a physiological parameter reading measured therewith. The control unit may instruct the device by broadcasting a corresponding instruction via at least one selected access station, the instruction being receivable by all devices in a coverage area of the at least one selected access station.

The system may further include at least one physiological parameter measuring device that is attachable to the first person for monitoring at least one physiological parameter of the first person. Each device has a device identifier and is being connected to the respective access station of the cell when it is within the cell.

According to another aspect of the invention, there is provided a physiological parameter measuring device. The device includes a transducer, a transmitter and a processor. The processor is connected to the transducer and the transmitter. The processor is adapted to control the transducer to at least intermittently measure a physiological parameter of a person and to control the transmitter to transmit a reading corresponding to the measured physiological parameter when it is determined that the reading has deviated from at least a predetermined threshold.

The device may further include a receiver connected to the processor and wherein the reading is also transmitted if the processor receives an instruction to do so via the receiver.

The device may further include a housing including a first portion, a second portion and a flexible medial portion connected between the first and the second portion. The device may be a thermometer for measuring the temperature of a person. The processor, transmitter and receiver may be accommodated within the first housing portion and the transducer may be supported on the second housing portion.

The first and the second portion may be bent towards each other to define a U-shaped device for hooking on a piece of clothing so that the transducer is in contact with the abdomen of a person for measuring a temperature thereat.

DETAILED DESCRIPTION

Hereafter, a preferred embodiment of the invention will be described in the context of a system for monitoring the body temperature of people who are mobile in a building. However, it is to be understood that the invention is usable in other physiological parameter monitoring systems for monitoring other physiological parameters, such as pulse rate, respiration rate, blood pressure, and blood glucose level, and even electrocardiogram signals of a group of people in a given area.

FIG. 1is a block diagram of a system2for constantly monitoring the body temperature of a group of people in a building according to an embodiment of the present invention. The system2includes a remote control unit4and a number of access stations6connected to the control unit4. The control unit4may be a server computer. The access stations6may be connected to the control unit4via a dedicated network or a local area network (LAN). The network may either be a wired network or a wireless network. An example of a wireless network is a network according to the IEEE 802.11b specifications. Each access station6in the system2has a unique station identifier (ID).

The access stations6are deployed to cover different locations of the building. The access stations6may be installed on the ceiling of each of the different locations. Each access station6has a range of operation that covers and thus defines a coverage area or cell8. Each access station6includes a first interface (not shown) that allows the access station6to be connected to the network and a second interface (not shown) that allows the access station6to communicate with one or more temperature sensing devices or thermometers10that are within its cell8. The first interface depends on the type of network. The second interface may be for supporting a wireless type of communication protocol, wherein the access station6may be able to simultaneously communicate with more than one thermometer10. Examples of such a wireless type of communication protocol are the existing Bluetooth, wireless LAN, IEEE 802.11b protocols.

Alternatively, a self-defined wireless protocol using amplitude modulation, frequency modulation, phase modulation, diffused infrared or infrared signal modulation is also possible. When using for example the Bluetooth protocol, an access station6can communicate with up to seven thermometers10at the same time. An access station6using such a protocol has a coverage area8of a radius of about ten meters around the access station6. In Bluetooth terms, the access station6is a master device and the thermometers10are slave devices.

Each thermometer10is able to at least intermittently transmit or broadcast a unique device identifier (ID) and a reading corresponding to a measured temperature as transmitted data. The access station6is able to pick up or receive the transmitted data, append its station ID to the data to form a data packet that is forwarded to the control unit4. Each access station6and thermometers10within its coverage area8may be considered to form a piconet. When a thermometer10moves from a first cell8into a second cell8, transmitted data of the thermometer will be received by an access station6of the first cell8and subsequently by another access station6of the second cell8. The access station6of the second cell8would then send another data packet to the control unit4. In this manner, the location of a thermometer10can be tracked based on the station ID of the access stations that receive the transmission of the thermometer10as the person moves about in the building.

At the control unit4, each received data packet is stored as a record in a temperature information table12as shown inFIG. 2A. In addition to the device ID, station ID, and temperature reading, the time at which the packet is received are also included in the record14. The time may also include a date. Such a temperature information table12is shown inFIG. 2A. The temperature information table12may be stored in any storage device (not shown), such as a hard disk, a floppy disk, a tape or the like, in the control unit4. The control unit4is able to process, analyze, organize and present these records using software applications, an example of which will be described later.

The thermometers10are described in more details next. Each of the thermometers10includes a temperature sensor20and a wireless communication module22connected to a processor24as shown inFIG. 3A. The communication module22may include a transmitter (not shown) or a transceiver (not shown). The transceiver includes a transmitter and a receiver. Each thermometer10also includes a device ID that is readable by the processor. The device ID may be hardwired in the thermometer10or programmed therein. The thermometer10may or may not include a display (not shown). A thermometer10without a display is smaller and thus is likely to be more comfortable for wearing on a person's body. For such a thermometer without a display, the temperature reading may be transmitted to a Bluetooth-enabled mobile phone or PDA carried by the person for display thereon. Alternatively, the reading may be simply displayed on a display screen (not shown) of the control unit4when the control unit4receives the data packet transmitted by the thermometer10.

The temperature sensor20is any transducer that is able to convert a temperature to a corresponding electrical signal. An example of such a transducer is a thermistor assembly. The processor24includes an internal analog-to-digital (A/D) converter with associated software (not shown) that converts the electrical signal to a temperature reading. The wireless communication module22is able to, under the control or direction of the processor24, transmit the temperature reading and its device ID in a data packet. The thermometer10at least intermittently measures a temperature and transmits the temperature reading. In other words, the thermometer can transmit data continuously, at intermittent intervals or at periodic intervals. In some embodiments, the thermometer10periodically, for example once every ten seconds, measures a temperature and transmits the temperature reading.

FIG. 3Bshows a plan view of a housing25of the thermometer10.FIGS. 3C and 3Dare side views of the housing25of thermometer10, shown in a straight and a bent position respectively. The housing25has a first body portion26for accommodating the processor24and the wireless communication module22. The housing25has a second temperature sensing portion28that supports the temperature sensor20. The temperature sensing portion28is connected to the body portion26via a flexible medial portion30that allows the thermometer10to be bent thereat. The flexible medial portion30may be of a resilient material, such as thermoplastic rubber, that allows the temperature sensing portion28to be bent over towards the body portion26to form a U shape. In this position of the thermometer10, the temperature sensor20is outward facing.

During use for measuring the temperature at the abdomen of a person, a holder32made of a hard material, such as hard plastic, is provided for supporting the thermometer10.FIG. 3Eis a drawing of the holder32. The holder32includes a clip34having two panels36. On one panel36of the clip34are two protruding members38that define a pocket40for receiving the body portion26of the thermometer10. On the other panel36of the clip is a catch (not shown) for receiving and holding the temperature sensing end28in place when the thermometer10is bent and placed in the holder32. The clip34can be conveniently attached to a waist portion of a pair of pants so that the temperature sensor20is in contact with the abdomen of the person. In this position, the body portion26of the thermometer faces away from the person.

The deployment of the system2for use in a building for tracking the movement and monitoring the temperature of a group of people in the building so that a person who is detected to have a physical condition, such as fever, can be located, is next described with the aid ofFIG. 4.FIG. 4shows a flowchart of a main sequence50of steps. The main sequence50starts in START step52and proceeds to a DIVIDE AREA step54, wherein the access stations6are deployed at different locations of the building. With each access station6defining a cell8, such a deployment serves to divide the building into identifiable cells8. An operator enters the location where each access station6is deployed as a record56in a station location table58as shown inFIG. 2B. Each record56thus includes two fields—a station ID field and a location field. The station IDs of the access stations6serve as location IDs of the cells8.

The main sequence50next proceeds to an ISSUE THERMOMETER step60, wherein each person arriving at an entrance of the building is provided or issued with a thermometer10. The device ID, name and contact details of the person issued with a thermometer10are entered as a record62into a name table64as shown inFIG. 2C. Each record62in this name table64therefore includes a device ID field, a name field and a contact details field. The person is made to wear the issued thermometer10such that his or her temperature may be at least intermittently taken using the thermometer10.

The main sequence50next proceeds to an OBTAIN AND TRANSMIT TEMP step66, wherein the thermometer10at least intermittently measures a temperature of the person and transmits a reading corresponding to the temperature along with its device ID.

The main sequence50next proceeds to a RECEIVE AND FORWARD step68when the person wearing the thermometer10enters a cell8adjacent to the entrance. An access station6serving the cell8receives the transmitted data of the thermometer10. As described above, the access station6then forwards the data along with its station ID in a data packet to the control unit4. In this manner, the reading and device ID becomes associated with the station ID.

The main sequence50next proceeds to PROCESS INFORMATION step70when the control unit4receives the data packet forwarded by the access station6. With the information obtained in the data packet, it is possible for the control unit4to know the location of the person in the building at a cell level.

The details of how the information is processed in the control unit4are next described. The main sequence50upon entering the PROCESS INFORMATION step70proceeds to a TEMP READING LOW? decision step72, wherein the control unit4determines if the temperature reading in the data packet is below a low-threshold value. If it is determined that the temperature reading is below the low-threshold value, the main sequence50proceeds to a GENERATE ALERT MSG step74, wherein the control unit4generates a first alert message based on information collected from the various tables12,58,64. The control unit4displays the first alert message on the display screen of the control unit4. The control unit4may also send the first alert message to a selected recipient, such as the operator, via a communications network, such as a public paging or mobile communications network (not shown).

The TEMP READING LOW? decision step72may be used to detect if the thermometer10is properly worn on the person. In this case, the low-threshold value may be set to a temperature of for example 32° C., which is lower than the normal body temperature range of 36.5 to 37.2° C. If the thermometer10is not properly worn or becomes dislodged from the person, the temperature reading would fall below the low-threshold value. For such a condition, the first alert message may, for example, be “USAGE ALERT: Mr. A's temperature is 31.9° C. at 1:25 pm, 2 Apr. 2003. He's in Conference Room B.” or simply “USAGE ALERT: Mr. A, who is in Conference Room B, may not be wearing his thermometer properly”. An operator upon receiving such a message may then approach Mr. A to check and ensure that he is wearing his thermometer10properly. The main sequence50next proceeds to an ENTER RECORD step76, which will be described shortly.

If it is determined in the TEMP READING LOW? decision step72that the temperature reading is not below the low-threshold value, the main sequence50proceeds to a TEMP READING HIGH? decision step78, wherein the control unit4compares the temperature reading of the thermometer10with a high-threshold value to determine if the temperature reading is above the high-threshold value. The high-threshold value may be set at 38° C. If it is determined that the temperature reading exceeds the high-threshold value, the main sequence50proceeds again to the GENERATE ALERT MSG step74. In the step74, the control unit4, recognizing from the station ID that the cell8is adjacent the entrance of the building, sends a second alert message to a security personnel stationed at the entrance to indicate that the person wearing the thermometer10has a higher than acceptable temperature. This second alert message may be “REFUSE ENTRY: Mr. A has a body temperature of 38.5° C.”. The security personnel may respond to the second alert message by escorting the person away for the person to be more thoroughly examined by a doctor for example.

If it is determined in the TEMP READING HIGH? decision step78that the temperature reading of the thermometer10is equal or less than the high-threshold value, the control unit4will not send an alert message to the security guard. The main sequence50then proceeds to the ENTER RECORD step76, wherein the control unit4creates a record in the temperature information table12from the received data packet. The control unit4updates a time field of the record with the time of receipt by the control unit4of the data packet so as to associate a time with the other fields of the record14. That is, each record in the temperature information table includes a device ID, a temperature reading, a station ID and a time information. In this manner, the control unit4captures the data packet in a record.

When no second alert message is received by the security personnel at the entrance as determined by the steps72,78, the person is allowed to enter and roam in the building. The thermometer10will at least intermittently transmit a temperature reading and its device ID. The main sequence50will loop around the OBTAIN AND TRANSMIT step66, the RECEIVE AND FORWARD step68and the PROCESS INFORMATION step70for each transmission by the thermometer10that is received by one of the access stations6. Over time, the control unit4will create a large number of records in the temperature information table12for each of the thermometers10. These records are thus available at a central location.

A scenario of the person moving into a Conference Room B in the building is next described. Let us assume that the person's temperature rises to 38.1° C. while in Conference Room B. The access station6covering Conference Room B will receive the temperature reading and device ID of the person's thermometer10and forward it to the control unit4as described above. The control unit4will detect that the person's temperature is above the high-threshold value in the TEMP READING HIGH? decision step78. The control unit4will then generate a third alert message, such as “FEVER ALERT: Mr. A's temperature is 38.1° C. at 1:25 pm, 2 Apr. 2003. He's in Conference Room B” from data obtained from the tables12,58,64. As with the case of the first alert message, the third alert message may be displayed on a display screen and/or sent to the operator. The operator upon receiving this third alert message may then inform the security personnel or a healthcare personnel to proceed to Conference Room B to escort Mr. A to a designated area so as to isolate him. In this manner, a person who has fever may be identified and located.

After the ENTER RECORD step76, the main sequence50proceeds to a CONTACT TRACE ACTIVATED? decision step80, wherein the control unit4determines if the operator has initiated the contact tracing application or feature. This contact tracing application may be automatically activated when a thermometer reading received by the control unit4is deemed to have exceeded the high-threshold value. Alternatively, the operator may initiate the feature with a selected record. If it is determined in this step80that the contact tracing feature is activated, the main sequence50proceeds to the PERFORM CONTACT TRACE step82, wherein the control unit8performs contact tracing by following a contact tracing sequence84as shown inFIG. 5.

The contact trace sequence84is described next with the aid ofFIG. 5. The contact trace sequence84starts in a START step86, wherein the control unit4extracts the records in the temperature information table12that were collected over a period of time. The period of time may be the past 10 days. The contact trace sequence84then proceeds to a READ A RECORD step88, wherein the control unit4reads a record from the extracted records. The contact trace sequence84then proceeds to an ID MATCH? decision step90, wherein the control unit4determines if the device ID in the read record is equal to the device ID of the selected record. If it is determined that the IDs in the two records match, the contact trace sequence84proceeds to a MORE RECORDS AVAILABLE? decision step92. If it is determined in the ID MATCH? decision step90that the device ID of the read record is not equal to the device ID of the selected record, the contact trace sequence84proceeds to an ID IN VICINITY? decision step94, wherein the control unit4determines if the thermometer10having the device ID in the read record had been in the vicinity, or physical proximity, of the thermometer10having the device ID of the selected record. In one embodiment, the thermometer10having the device ID of the read record is considered to be in the vicinity of the thermometer10having the device ID in the selected record if the read record has the same station ID and about the same time as the selected record. In another embodiment, the thermometer10having the device ID of the read record is considered to be in the vicinity of the thermometer10having the device ID in the selected record if the read record has the same station ID and about the same time as any one of all the extracted records having the same device ID as the selected record.

If it is determined in this ID IN VICINITY? decision step94that the thermometer10from which the read record is obtained is not in physical proximity of the thermometer10having the device ID in the selected record, the contact trace sequence84proceeds to the MORE RECORDS AVAILABLE? decision step92. If it is determined that the two thermometers were in the same vicinity, the contact trace sequence84proceeds to a LOG RECORD step96, wherein the control unit4logs the read record into a contact tracing table (not shown). The contact trace sequence84next proceeds to the MORE RECORDS AVAILABLE? decision step92, wherein the control unit4determines if there are still further records amongst the extracted records to be read. If it is determined that there are more records to be processed, the contact trace sequence84returns to the READ A RECORD step88. Otherwise, the contact trace sequence84ends in an END step98.

The control unit4uses the records in the contact tracing table, more specifically the device ID in the records, to access the name table64to generate a contact trace list (not shown). The contact trace list may also be displayed as messages on the display screen, such as “CONTACT TRACED: Mr. C is with Mr. A in Conference Room B at 1:25 pm, 2 Apr. 2003,” if the selected record is the one that is processed to cause the generation of the third alert message described above. The operator who reads the messages can then act accordingly, such as to contact or to serve the people whose names appear in the contact trace list with quarantine orders.

In the system2above, the thermometer10is described to be intermittently or periodically transmitting data that is picked up by the access stations6. Such intermittent or periodic transmission of data, especially those involving radio frequency transmissions, may consume significant battery power and drain the battery in a short period of time. It is therefore desirable to minimize the number of such transmissions by the thermometers10so as to conserve battery power.

One method of minimizing the number of transmissions will be described with the aid of flowcharts inFIGS. 6A and 6B, which show a master sequence110and a slave sequence112implemented in the control unit4and the thermometer10respectively.

The slave sequence112in the thermometer10starts in a START step114, when a temperature reading is obtained. The slave sequence112next proceeds to the TRANSMIT READING? decision step116, wherein the processor24determines if a transmit-reading instruction from the control unit4has been received previously by the thermometer10. If it is determined that the transmit-reading instruction is received, the slave sequence112proceeds to a TRANSMIT DATA step118, wherein the thermometer10transmits data as described above.

However, if it is determined that the transmit-reading instruction is not received, the slave sequence112proceeds to a TEMP READING HIGH? decision step120, wherein the processor24compares the temperature reading with a transmit-threshold value. If it is determined that the temperature reading exceeds the transmit-threshold value, the slave sequence proceeds to the TRANSMIT DATA step118to transmit data as described above. After the TRANSMIT DATA step118, the slave sequence112ends in an END step122. If it is determined that the temperature reading is equal or below the transmit-threshold value, the slave sequence112proceeds to the END step122without the thermometer10transmitting any data. With such a sequence of operation, the thermometer10transmits data only when a person is suspected of running a temperature, i.e. having a fever. The transmit-threshold value may be set to be equal or slightly lower than the high-threshold value. For simplicity, the transmit-threshold value may be set to a fixed value for all people. As an example, the transmit-threshold value may be set to 37.5° C. if the high-threshold value is set to 38° C.

The corresponding master sequence110in the control unit4is next described. The master sequence starts in a START step124, wherein the control unit4receives a temperature reading, a device ID, and a station ID from an access station6as described above. The master sequence110next proceeds to a TEMP READING HIGH? step126, wherein the control unit4compares the temperature reading with the transmit-threshold value. If it is determined that the temperature reading does not exceed the transmit-threshold value, the master sequence110ends in an END step128.

If however, it is determined in the TEMP READING HIGH? decision step126that the temperature reading exceeds the transmit-threshold value, the master sequence110proceeds to an ISSUE TRANSMIT-READING INSTRUCTION step130, wherein the control unit4directs the access station6through which the temperature reading is received to broadcast a transmit-reading instruction that is receivable by the thermometers10in its cell8. Alternatively the control unit4may direct other access stations6or all access stations6to transmit the transmit-reading instruction. The master sequence110next proceeds to the END step128. In this manner the thermometers10that are in the cell8would be able to receive the transmit-reading instruction and accordingly transmit data.

A scenario is next described to illustrate the operation of the master and the slave sequences110,112. Suppose Mr. A is in Conference Room B together with Ms. X, Ms. Y and Mr. Z. At 1 pm, their body temperatures are all below the transmit-threshold value, which is set at 37.5° C. Accordingly, their thermometers10and the access station6in the Conference Room B do not transmit any data. Then at 1:25 pm, Mr. A's temperature is detected by his thermometer10to be at 37.6° C., i.e. higher than the transmit-threshold value of 37.5° C. Mr. A's thermometer10will then, according to the slave sequence112, transmit data that contains the temperature reading and its device ID. The access station6picks up the transmission and forwards the transmitted data along with the station ID to the control unit4as described above. The control unit4, according to the master sequence110, detects that Mr. A's temperature is above the transmit-threshold value and sends a transmit-reading instruction to one or more access stations6covering Conference Room B. The thermometers10on Ms. X, Ms. Y and Mr. Z, who are in the Conference Room B will receive the transmit-reading instruction, and they will accordingly start to transmit their respective temperature readings and device IDs. The one or more access stations6will receive these transmissions and forward them to the control unit4. With these transmitted data, the control unit4is able to capture data that shows who is in the vicinity or physical proximity of Mr. A at the moment when Mr. A's temperature is detected to exceed the transmit-threshold value.

It the system2is solely for locating a person suspected to run a temperature, i.e. have a fever, or to not be wearing his or her thermometer10properly, there is no need for the master and slave sequences110,112described above. In such a case, the thermometer after obtaining a temperature reading compares it with a TH1 threshold value and a TH2 threshold value. If the temperature reading is determined to be higher than the TH1 threshold value or lower than the TH2 threshold value, the thermometer10will transmit data so that the control unit4is alerted. Otherwise, the thermometer10will not transmit any data. The TH1 threshold value may be the same as the high-threshold value of 38° C. and the TH2 threshold value may be the same as the low-threshold value of 32° C.

Another aspect of the above system2may be improved. This aspect relates to the accuracy of a temperature reading obtained from a person's abdomen. It is generally known that a temperature taken orally, that is by placing the temperature sensing end28of a thermometer10under a person's tongue, gives a reasonably accurate indication of the core body temperature of the person. However, the oral method is not appropriate for continuous temperature monitoring because it is both uncomfortable and inconvenient to have a thermometer10stuck in the mouth for a long period of time. There are certain parts of the human body, such as the armpit, abdomen or wrist, which are more comfortable and convenient for continuous temperature monitoring. However, measurement from these body parts usually does not give a reading that reflects the core body temperature. The temperature measured from these parts could be significantly lower (e.g., 0.5 to 3° C.) than that measured from the mouth. One usual practice is to add a correction factor, that is an average value obtained from the population, to the measured temperature obtained from a body part. For example, a correction factor of 0.5° C. may be added to the temperature measured from the armpit of 36.5° C. to give a temperature reading of 37° C., which is closer to the actual core body temperature. As the difference in temperature taken at the armpit and mouth varies from person to person, the use of a single common correction factor may not result in an accurate determination of the core body temperature. It is thus desirable to determine a temperature correction factor for each individual.

FIG. 7shows a flowchart of a calibration sequence132for obtaining a correction factor for use in a thermometer10issued to a person. The calibration sequence132starts in a START step134, when a calibration mode of the thermometer10is activated, for example by the person pressing a button (not shown) on the thermometer10. The calibration sequence132next proceeds to a TAKE ORAL TEMPERATURE step136, wherein the thermometer10prompts the person to place the thermometer10in his or her mouth beneath the tongue for the oral temperature to be taken. The prompt may be in the form of a lighted LED (not shown). The thermometer10may produce an alert signal, either audio or visual, to indicate that the oral temperature is taken and prompt the person to place the thermometer10at his or her abdomen for the abdomen temperature to be taken. The person would then place the thermometer10into the holder32and clip the holder32onto his or her pants as described above. At this point, the calibration sequence132proceeds to a TAKE ABDOMEN TEMPERATURE step138, wherein the thermometer10measures the abdomen temperature. The calibration sequence132next proceeds to a CALCULATE CORRECTION FACTOR step140, wherein the thermometer10calculates a correction factor based on the oral temperature and the abdomen temperature. The corrector factor may simply be the difference between the oral temperature and the abdomen temperature. The correction factor is stored in the thermometer10.

The calibration sequence132ends in an END step142, wherein the thermometer10exits the calibration mode and switches back to a temperature monitoring mode. In the temperature monitoring mode, the thermometer10after obtaining a temperature reading, adjusts it by including, for example by adding, the correction factor before transmitting it. In this manner, the adjusted temperature reading which is transmitted is closer to the core body temperature of the person. Such a calibration sequence132may be performed when the person is issued with the thermometer10at the entrance of a building or when the person is allowed entry into the building after the person is initially determined to be without a fever.

A further aspect of the system2may be improved. This further aspect relates to the high-threshold value used for determining if a person has fever. The system2is described above to have a single common high-threshold value for all people. Since the normal temperature varies from person to person, it may be desirable to determine a high-threshold value for each individual person.

One way of determining a personal high-threshold value is by statistically computing the high-threshold value using the most recently obtained temperature readings of a person. These most recently measured temperature readings may either be stored in the thermometer10or in the control unit4.

A threshold determination sequence150in the thermometer10for statistically computing a high-threshold value for a person is next described with the aid ofFIG. 8. The threshold determination sequence150starts in a START step152, when a person presses a button (not shown) on the thermometer10and then wears the thermometer10. The method proceeds to a PERIODIC MEASUREMENT step154, wherein the thermometer10periodically, for example once every ten seconds, takes and stores a temperature reading of the person. The sequence150next proceeds to an ENOUGH DATA COLLECTED? decision step156, wherein the thermometer10determines if the number of temperature readings has reached a predetermined number. If it is determined in this step156that the number of temperature readings is below the predetermined number, the sequence150loops around the ENOUGH DATA COLLECTED? decision step156waiting for the number of readings taken to reach the predetermined number, such as one hundred readings. When the number of readings reaches the predetermined number, the sequence150exits the ENOUGH DATA COLLECTED? decision step156and proceeds to COMPUTE HIGH_THRESHOLD step158. In this step158, the processor24in the thermometer10may calculate the high-threshold value for the person using the following formula:
high-threshold value=μ+kσ,wherein μ is the mean and σ is the standard deviation of the predetermined number of readings, and k is a positive number.

If the collected temperature readings are normally distributed and if k=3, 99.9% of the temperature readings will then be less than the high-threshold value computed according to the formula above.

Alternatively, the high-threshold value may simply be set to be a sum of a maximum value in the temperature readings and a margin value of for example 0.5° C. As an example, the maximum value of the predetermined number of temperature readings is 37.5° C. and the resultant high-threshold value would be 38° C. A single temperature reading may also be used to determine the high-threshold value.

The high-threshold value may be entered into the control unit4by the operator or it may be transmitted to the control unit4via the access station6using a designated data packet. If the control unit4receives such a high-threshold value from a thermometer10, the control unit4would use this high-threshold value for future comparison in the TEMP READING HIGH? decision step78in the main sequence50, otherwise the control unit4simply uses the default common high-threshold value available in the control unit4. The threshold determination sequence150ends in an END step160.

It should be noted that the method of determining a high-threshold value just described is also applicable for determining the other above-mentioned threshold values, such as the low-threshold value, the transmit-threshold value, the TH1 and TH2 threshold values.

It should also be noted that the method of determining a high-threshold value may be performed on the control unit4instead of the thermometers10. In such a case, the high-threshold value may be a single common high-threshold value that is determined based on the temperature readings received from all thermometers10whose readings are captured by the control unit4.

Although the invention is described as implemented in the above-described embodiment, it is not to be construed to be limited as such. For example, it is not necessary for the system to include multiple access stations6. A system including only a single access station6will also work. In such a case, the access station6may be integrated with the control unit4. That is, the access station6communicates with the control unit4via internal buses rather than through a physical communication link. Such a system may be deployed at “check points”, such as at entrances to buildings, offices, hospitals, and at immigration check points of airports or border crossings. When so deployed, the system is used not so much for tracking the location of people but merely for “scanning” the body temperature of people passing through these check points. A person going through one of these check points is required to have his or her temperature taken using the thermometer as described above. The reading of the thermometer will be transmitted to the access station. The control unit in turn receives the temperature reading via the access station. If the reading is determined by the control unit to be above a predetermined high-threshold value, the person may be refused entry so that remedial action may be taken, such as getting the person to consult a doctor and placing the person under quarantine.

As another example, a system for home application may include a Bluetooth-enabled mobile phone or personal digital assistant (PDA) as a control unit. In such a case, a Bluetooth repeater is used as an access station. The Bluetooth repeater is a device that simply re-transmits the signal that it receives. The thermometer in such a system includes a Bluetooth transceiver.

As yet another example, the thermometer may further include a panic button that may be actuated for the thermometer to transmit an emergency request for medical attention that includes the device ID of the thermometer. An access station in the vicinity of the thermometer receives the transmitted emergency request and forwards it together with its station ID to the control unit. The control unit upon receiving the emergency request displays a message on the display screen. The message may be “WARNING: Mr. A, who is in Conference Room B, requires immediate attention. Message logged at 1:25 pm, 2 Apr. 2003.” The operator can then summon healthcare personnel to attend to Mr. A immediately.

As yet a further example, the thermometer, which contains a unique device ID, can also double up as a security access device. For example, when a person who carries a thermometer approaches the entrance to a secured area, an access station at the entrance could authenticate the device ID and allow or deny access to the person accordingly.

As yet another further example, dividing an area into cells may involve deploying a transmitter in each of several locations of a building. Each transmitter is adapted to transmit a respective location identifier as a beacon. As each device moves into a location, the device is able to receive the transmitted location identifier and associate it with a reading and a time at which the reading is obtained using the device. The associated reading, time and location identifier may be transmitted by the device to a remote location each time a reading is obtained. Alternatively, the associated reading, time and location identifier, along with the device identifier may be stored in the device for uploading to a remote location at a later time. Although the latter implementation does not allow immediate detection, identification and location of a person having a physical condition, the data collected and stored in the device allows those who have been in physical proximity with the person at about the time when the person develops the physical condition to be subsequently identified. The data may also be used for identifying those who have been in physical proximity with the person a selected period of time prior to the person being detected only subsequently to have a physical condition. The location identifier may also be information recorded on a tag at each location of the building. In such a case, the thermometer may be used to read the tag. If the thermometer is used as a security access device as described above, the location identifier may be transmitted to the thermometer when it is used for gaining access to each location.