WO2014202135A1

WO2014202135A1 - A system and a method for determining physiological movements of a subject

Info

Publication number: WO2014202135A1
Application number: PCT/EP2013/062790
Authority: WO
Inventors: Rupa MINASAMUDRAM; Balaji Teegala
Original assignee: Siemens Aktiengesellschaft
Priority date: 2013-06-19
Filing date: 2013-06-19
Publication date: 2014-12-24

Abstract

The present invention relates to a system (3) for determining physiological movements of a part (5) of a subject (2) and a method thereof. The system (3) comprises a sensor module (6) and a frequency processing unit (7) operably coupled to each other. The sensor module (6) generates an electric signal (11) of a certain frequency (f) that uniquely corresponds to physiological dimension (4) of the part (5) of the subject (2). The frequency processing unit (7) determines the physiological dimension (4) of the part (5) of the subject (2) corresponding to the frequency (f) of the electric signal (11) generated thereof.

Description

A system and a method for determining physiological movements of a subject

The present invention relates to the field of determining physiological movements, and in particular to a system and a method for determining physiological movements of a subject. Determination of physiological movements of a subject plays a significant role in the field of healthcare. The

physiological movements cause variations in physiological dimensions of a part of the subject's body. Healthcare professionals utilise the information rendered by the

physiological movements of a certain part of the subject's body to assess the proper functioning of one or more organs associated thereof which contribute to the physiological movements. An assessment of the physiological dimensions of the part of the subject's body is an indicator of the

healthiness of the one or more organs contributing to the physiological movements. Furthermore, by the determination of one or more anomalies in the physiological movements

contributed by the part of the subject's body, it is possible to identify, diagnose, and ascertain potential malfunctioning of the one or more organs associated thereof.

The aforementioned matter is elucidated by means of the following example. During respiration, which is a periodic event, cyclical movements of the abdominal region are

experienced by the subject. The movements of the abdominal region cause corresponding variations of the dimensions of the abdominal region. The cyclical movements of the abdominal region follow a set pattern. Therefore, one or more anomalies in the movements of the abdominal region are indicators of certain disorders pertaining to the respiratory system of the subject. For example, the anomalies in the respiratory organs, such as Tachypnea or Bradypnea, can contribute to anomalous breathing of the subject, and can be potentially lethal to the healthiness of the subject. Herein, the

anomalous breathing of the subject can be diagnosed by determining anomalies in the set pattern of the cyclical movements of the abdominal region. I.e., the anomalies may be determined by determining the anomalous variations of the dimensions of the abdominal region experienced during the anomalous movements of the abdominal region.

Therefore, systems for accurately determining physiological dimensions of the part of the subject's body and the

variations thereof are important for assessing the

physiological movements contributed by the part of the subject' s body. US6062216 relates to a sleep apnea detector system, which is a wearable respiration sensor, which detects changes in physiological movements of the chest and the abdominal regions during breathing. The respiration sensor is based on an optical interferometric technique. However, the

respiration sensor is bulky, susceptible to interference caused due to vibrations of the sensor, misalignment of the sensor, and the thermal drift of the sensor.

US7559902 relates to a physiological monitoring garment for detecting physiological movements based on the technique of capacitive sensing. However, monitoring garment is bulky and the subject is mandated to wear the bulky monitoring garment for the detection of the physiological movements, which can be extremely cumbersome.

The present invention aims to obviate the aforementioned disadvantages posed by the existing techniques that are used for the determination of the physiological dimension of a part of a subject.

The determination of the physical dimension over a certain period of time enables the determination of the physiological movement of the part of the subject. An object of the present invention is to propose a simple, a reliable, a sturdy, and a cost-effective system and a method for determining physiological movements of a subject. The aforementioned object is achieved by a system according to claim 1, and a method according to claim 16.

The underlying object of the present invention is to propose a system to determine a physical dimension of a part of a subject in a simple, a reliable, a sturdy, and a cost- effective manner. A system elucidated herein for achieving the aforementioned objective primarily comprises a sensor module and a frequency processing unit. The sensor module is configured to detect the physiological dimension of the part of the subject, and generates electric signals of distinct frequencies. Each distinct frequency of the electric signal corresponds to a distinct physiological dimension of the part of the subject. The frequency processing unit and the sensor module are operably coupled to one another. The frequency processing unit receives the electrical signals and

determines the physiological dimension of the part of the subject corresponding to the frequency of the electric signal . In accordance with an embodiment of the present invention, the sensor module comprises a sensor. The sensor is such that the dimension of the sensor varies in accordance with the physiological dimensional variation of the part of the subject. Therewith, the physiological dimensional variations of the part of the subject can be determined from the

dimensional variations of the sensor in a reliable manner.

In accordance with another embodiment of the present

invention, the frequency of the electric signal is a function of the dimension of the sensor. Therewith, a distinct

frequency can be generated that corresponds to a distinct physiological dimension of the part of the subject. The determination of the frequency of the electric signal can be achieved using minimal and conventional hardware. Therewith, the determination of the dimension of the part of the subject is simplified. In accordance with yet another embodiment of the present invention, the frequency of the electric signal is the resonant frequency of the sensor. It is easier to excite the sensor to operate at its resonant frequency compared to other frequencies. Therewith, the effort required to generate the electric signal is reduced.

In accordance with yet another embodiment of the present invention, the resonant frequency of the sensor is inversely proportional to the dimension of the sensor.

In accordance with yet another embodiment of the present invention, the dimension of the sensor is the length of the sensor. It is easier to design sensors in which the length of the sensor is variable in accordance with the physiological dimension of the part of the subject.

In accordance with yet another embodiment of the present invention, the sensor comprises an antenna. The antenna is configured to undergo dimensional variations based on the variation of the physiological dimension of the part of the subject. The frequency of the electrical signal generated by the sensor module is a function of the dimension of the antenna. Thus, it is easier to generate electrical signals of distinct frequencies based on the dimensional variations of the antenna.

In accordance with yet another embodiment of the present invention, the antenna is capable of operating in the Ultra High Frequency range. Therewith, the frequency resolution of the electrical signals generated thereof can be enhanced and the resolution of the physiological dimension of the part of the subject is correspondingly increased too. In accordance with yet another embodiment of the present invention, the antenna is a fluidic antenna. Therewith the operational life of the antenna is increased, because the fluidic antenna is capable of enduring high amounts of fatigue and is capable of returning to their original shape without loss of electrical conductivity.

In accordance with yet another embodiment of the present invention, the antenna is a textile antenna. The textile antenna can be realised as a piece of garment that can be worn by the subject, such that a portion of the garment comprising the textile antenna is positioned over the part of the subject for assisting the determination of the

physiological dimension of the part of the subject and the physiological movements arising due to the variations

thereof .

In accordance with yet another embodiment of the present invention, the frequency processing unit comprises a

frequency demodulator module and processing module. The frequency demodulator module demodulates the electric signal to determine the frequency of the electric signal. The processing module processes the frequency of the electric signal to determine the physiological dimension of the part of the subject.

In accordance with yet another embodiment of the present invention, an attaching means is provided for attaching the sensor to the part of the subject. The sensor is therewith attached such that a change of the physiological dimension of the part of the subject results in a change of dimension of the sensor. Therewith, it is provides a provision to affix the sensor firmly on to the part of the subject thereby obviating the slippage of the sensor during the process of determining the physiological dimension of the part of the subj ect . In accordance with yet another embodiment of the present invention, a power supply unit is provided for providing electric power to the sensor module and/or the frequency processing unit. Therewith, it is possible to realise the system as an independent and stand-alone unit thereby

obviating the requirement of external power supplies. Thus, the portability of the system is enhanced. Furthermore, with the availability of onboard power, the sensor can now be realised as an active sensor, whereby the accuracy of the determination of the physiological dimension of the part of the subject is further enhanced.

In accordance with yet another embodiment of the present invention, the frequency processing unit is integrated into the sensor module. A transmitting means is provided for providing the resonant frequency of the electric signal and/or the physiological dimension of the part of the subject to a data processing unit for the visualisation thereof.

Herein, the entire system is capable of being realised as a miniaturized and a portable unit such as an Application

Specific Integrated Circuit, a System on Board Chip, et cetera .

A method for the determination of the physiological dimension of the part of the subject is herewith provided. The

frequency of the electric signal is determined from the electric signal generated by the sensor. The frequency corresponds to a certain physiological dimension of the part of the subject. Subsequently, the physiological dimension of the part of the subject is determined from the frequency of the electric signal.

In accordance with an embodiment of the present invention, the electric signal is demodulated for determining the frequency of the electric signal. The frequency of the electric signal is thereafter processed for determining the physiological dimension of the part of the subject. In accordance with an embodiment of the present invention, the determined frequency is processed based on a calibration relationship. The relation between the physiological

dimension of the part of the subject and the dimension of the sensor is defined by the calibration relationship. The calibration relationship is a reliable denotation of the transfer characteristics of the sensor. Therewith, the accuracy of the determination of the physiological dimension of the part of the subject based on the determined frequency of the electric signal is enhanced further.

The aforementioned and other embodiments of the present invention related to a system and a method for determining physiological movements of a subject will now be addressed with reference to the accompanying drawings of the present invention. The illustrated embodiments are intended to illustrate, but not to limit the invention. The accompanying drawings contain the following figures, in which like numbers refer to like parts, throughout the description and drawings.

The figures illustrate in a schematic manner further examples of the embodiments of the invention, in which:

FIG 1 depicts a subject being medically examined in a medical room wherein a system is provided for determining physiological dimension of a part of a subject,

FIG 2 depicts the system referred to in FIG 1

comprising a sensor module and a frequency processing unit,

FIG 3 depicts a graph that denotes an exemplary

relation between the dimension of a sensor comprised in the sensor module referred to in FIG 2 and the frequency of the electric signal produced thereof, FIG 4 depicts a flowchart of a method for determining physiological dimension of the part of the subject referred to in FIG 1,

FIG 5a depicts temporal variations of the dimension

the sensor referred to in FIG 3,

FIG 5b depicts temporal variations of the resonant

frequency of the sensor referred to in FIG 3, and

FIG 5c depicts temporal variations of the physiological dimension of the part of the subject referred to in FIG 1.

An exemplary medical room 1 to perform a medical examination and/or an observation of a subject 2 is depicted in FIG 1.

In accordance with an embodiment of the present invention, a system 3 is provided for determining one or more

physiological dimensions 4 of a part 5 of the subject 2.

Physiological movements of the part 5 of the subject 2 are thereafter determined based on the determined physiological dimensions 4 of the part 5 of the subject 2. A general arrangement of the system 3 for determining the physiological dimensions 4 of the part 5 of the subject 2 is depicted in FIG 1, and it may be noted herein that the system 3 is elucidated in detail with reference to FIG 2. Herein, "the subject 2 " refers to a living organism, such as a human being, an animal, et cetera. The subject 2 can undergo a clinical test, diagnosis, et cetera, for the purpose of observation, physiotherapy, treatment, medical intervention, surgery, et cetera.

Herein, "the part 5" of the subject 2 refers to an exemplary physical region of the subject 2, wherein the physical region undergoes physiological movements during the functioning of one or more organs and/or joints associated thereof. For example, the physical region can be an abdominal region, a thoracic region, a knee joint, an ankle joint, et cetera. Herein, "the physiological movement" is to be construed as a movement of the part 5 of the subject 2, wherein the movement results in variation of one or more physiological dimensions

4 of the part 5 of the subject 2 during the functioning of one or more organs and/or joints associated thereof. The physiological dimensions 4 are to be construed as the length, the width, et cetera of the part 5 of the subject 2. The part

5 of the subject 2 is either elongated or shortened during the occurrence of the physiological movement. For example, the physiological movements, which are caused due to the respiration cycle of the subject 2, result in movements of the abdominal region of the subject 2, wherein the one or more physiological dimensions of the abdominal region vary in accordance with the physiological movements caused due to the respiration cycle. Similarly, the

physiological movements, which caused due to the ambulation of the subject 2, result in movements of the knee joint of the subject 2, wherein the one or more physiological

dimensions of the knee joint vary in accordance with the physiological movement caused due to the ambulation of the subject 2.

Herein, by the determination of the physiological movements associated with the part 5 of the subject 2, it is possible to assess the healthiness of the one or more organs

associated with the part 5 of the subject 2. For example, by determination of the abdominal movements of the subject 2, the propriety of the breathing of the subject 2 can be determined. The propriety of the breathing of the subject 2 is an indication of the behaviour and the healthiness of the lungs of the subject 2. Hereinafter, for the purpose of elucidation of the present invention in specific, the subject 2 is considered to be a human being, the part 5 of the subject 2 is considered to be the abdominal region of the subject 2, and the physiological movement is considered to be the movements of the abdominal region 5 caused due to the respiration cycle of the subject 2. The physiological dimension 4 of the abdominal region 5 of the subject 2 is considered to be a dimension of the

abdominal region 5, wherein the physiological dimension 4 of the abdominal region 5 varies in accordance with the

movements of the abdominal region 5. For example, the

physiological dimension 4 of the abdominal region 5 can be a length of the abdominal region 5, a width of the abdominal region 5, the girth of the abdominal region 5, et cetera.

The system 3 according to the present invention along with the components associated thereof is depicted in FIG 2.

Reference is also made herein to FIG 1 for the purpose of elucidation of FIG 2. The system 3 primarily comprises a sensor module 6 and a frequency processing unit 7. The sensor module 6 and the frequency processing unit 7 are operably coupled to each other, thereby facilitating the exchange of necessary control and data signals between one another. A power supply unit 8 is provided for supplying necessary electric power to both the sensor module 6 and the frequency processing unit 7, thereby enabling the proper functioning of the sensor module 6 and the frequency processing unit 7. The sensor module 6 comprises a sensor 9 and an attaching means 10, wherein the attaching means 10 purports to affix the sensor 9 onto the abdominal region 5 of the subject 2. Herein, by means of affixation of the sensor 9 onto the abdominal region 5, the fidelity of transduction of the physiological dimension 4 of the abdominal region 5 and/or the variations of the physiological dimension 4 of the abdominal region 5 during physiological movements of the abdominal region 5, into appropriate electric signals 11 is facilitated. It may also be noted herein that the slippage of the sensor 9 from the abdominal region 5 is prevented, because the sensor 9 can be held firmly onto the abdominal region 5 by the attaching means 10. Therewith, the accuracy of the transduction is enhanced. Herein, the attaching means 10 can be realised using a glue-based sticker, a vacuum-based holder, a wrap-around belt, et cetera.

According to the present invention, the sensor 9 purports to transduce the physiological dimension 4 of the abdominal region 5 into an electric signal 11 of a certain frequency f. The process of transduction involves generation of the electric signal 11 of the certain frequency f which

corresponds to the physiological dimension 4 of the abdominal region 5. Herein the sensor 9 is such that distinct

physiological dimensions 4 of the abdominal region 5, which arise due to the respiration cycle of the subject 2, are correspondingly transduced into the electric signals 11 of the distinct frequencies f. I.e. each physiological dimension 4 of the abdominal region 5 is uniquely represented by a corresponding frequency f . This is achieved by influencing a dimension 12 of the sensor 9 to undergo variations in

accordance with the variation of the physiological dimension 4 of the abdominal region 5. The dimension 12 of the sensor 9 in accordance with the present invention is the length of the sensor 9.

In accordance with an exemplary embodiment of the present invention, the sensor 9 is an antenna, and the antenna 9 is affixed to the abdominal region 5 of the subject 2 using the attaching means 10. The antenna 9 is such that the length 12 of the antenna 9 is capable of undergoing variations in accordance with the dimensional variations of the abdominal region 5, which are caused due to the physiological movements of the abdominal region 5 which are in turn attributed to the respiration cycle of the subject 2. The antenna 9 can be realised as a flexible patch antenna, a fluidic antenna, a textile antenna, a Radio Frequency Identification Tag, and the like, wherein the length 12 of the antenna 9 is capable of being facilely influenced based on the physiological movements of the abdominal region 5 of the subject 2 whereto the antenna is affixed.

The frequency f of the electric signal 11 generated by the sensor module 6 is a function of the length 12 of the antenna 9, wherein the frequency f of the electric signal 11 is inversely proportional to the length 12 of the antenna 9. It may be noted herein that the frequency f of the antenna 9 is construed to be the resonant frequency f_r of the antenna 9. The relation between the resonant frequency f_r of the antenna 9 and the length 12 of the antenna 9 is denoted by the following equation (1) :

Herein ^xc' is the velocity of light in vacuum, ^Λ1' is the length of the antenna 9, and ^λε' is the effective dielectric constant of the material of the antenna 9.

Thus, it may be noted herein that different lengths 12 of the antenna 9 result in electric signals 11 of correspondingly different resonant frequencies f_r. Since the length 12 of the antenna 9 is based on the physiological dimension 4 of the abdominal region 5 of the subject 2, the resonant frequency f_r of the electric signal 11 generated by the antenna 9 is therefore an indication of the physiological dimension 4 of the abdominal region 5 of the subject 2.

In an exemplary aspect of the present invention, the sensor module 6 further comprises an oscillator circuit 13. The oscillator circuit 13 can be configured to generate the aforementioned electric signals 11 of respective resonant frequencies f_r corresponding to the respective lengths 12 of the antenna 9. The functioning of the oscillator circuit 13 is analogous to the frequency modulation, wherein the frequency f of the electric signal 11 generated thereof is based on the length 12 of the antenna 9. This is well known to a person skilled in the art and is not elucidated herein for the purpose of brevity.

The electric signal 11 generated by the sensor module 6 is thereafter provided to the frequency processing unit 7 for determining the resonant frequency f_r of the electric signal 11. The frequency processing unit 7 primarily comprises a frequency demodulator module 14 and a processing module 15.

The frequency demodulator module 14 demodulates the generated electric signal 11 for determining the resonant frequency f_r of the electric signal 11, in order to determine the length 12 of the antenna 9. The resonant frequency fr can be

determined based on the following equation (2) :

(2) An exemplary graph 16 depicting the relation between the length 12 of the antenna 9 and the corresponding resonant frequency fr thereof based on the aforementioned equation is illustrated in FIG 3. The abscissa 17 of the graph 16 denotes the length 12 of the antenna 9 and the ordinate 18 of the graph 16 denotes the resonant frequency fr thereof. It may be observed from the graph 16 that each length 12 of the antenna 9 is uniquely mappable to a corresponding resonant frequency fr of the antenna 9. Two exemplary points 19,20 are therein indicated. At the exemplary point 19, the length 12 of the antenna 9 is at its lowest (indicated as L_mi_n on the abscissa 17), which purports to be the highest resonant frequency (indicated as f_r max on the ordinate 18) of the antenna 9. Whereas at the exemplary point 20, the length 12 of the antenna 9 is at its highest (indicated as L_max on the abscissa 17) which purports to be the lowest resonant frequency (indicated as f_{r m}i_n on the ordinate 18) of the antenna 9.

Herein, in accordance with another embodiment of the present invention, the antenna 9 is an Ultra High Frequency (UHF) based antenna 9. Therewith, the resolution of frequency f of the electric signal 11 can be enhanced, and therewith the accuracy of determination of length 12 of the antenna 9 and therewith the accuracy of the determination of the

physiological dimension 4 of the abdominal region 5 o the subject 2 can be consequently enhanced. Furthermore, the signal to noise ratio can be enhanced by means of the UHF antenna 9. Now referring back to FIG 2, information representing the length 12 of the antenna 9 is provided to the processing module 15 for determining the physiological dimension 4 of the abdominal region 5 that corresponds to the length 12 of the antenna 9. The processing module 15 determines the physiological dimension 4 of the abdominal region 5 from the resonant frequency f_r as determined by the frequency

demodulator module 14 based on a calibration relationship. Herein, the calibration relationship is a mathematical relation that defines the relation between the physiological dimension 4 of the abdominal region 5 and the corresponding length 12 of the antenna 9. It may be noted herein that calibration relationship can be linear, quadratic,

polynomial, et cetera. The calibration relationship can be determined experimentally in accordance with any of the well- known techniques, and the determination of the calibration relationship is herein not elucidated for the purpose of brevity .

In accordance with another aspect of the present invention, the processing module 15 can comprise a lookup table. The lookup table can comprise numerical values of different lengths 12 of the antenna 9, and the corresponding numerical values of the different physiological dimensions 4 of the abdominal region 5. Thus, the processing module 15 can receive the length 12 of the antenna 9 as the input, can refer to the lookup table, and can fetch the physiological dimension 4 of the abdominal region 5 corresponding to the length 12 of the antenna 9.

According to an embodiment of the present invention, the system 3 also comprises a transmitting means 21, which is communicatively coupled to the sensor module 6 and the frequency processing unit 7. The transmitting means 21 can be configured to transmit the electric signal 11 generated by the sensor module 6, the resonant frequency f_r of the antenna 9 as determined by the frequency processing unit 7, and/or the physiological dimension 4 of the abdominal region 5 as determined by the frequency processing unit 7, et cetera, to an external data processing unit 22, such as a general purpose computer. The data processing unit 22 and the

transmitting means 21 are communicatively coupled to one another. The communicative coupling between the transmitting means 21 and the data processing unit 22 can be wired, wireless, or a combination thereof.

Furthermore, in another embodiment of the present invention, the sensor module 6 and the frequency processing unit 7 can be integrated to form a single unit, such as an integrated circuit, a system on chip, et cetera. In such a case, the transmitting means 21 and the data processing unit 22 can be wirelessly coupled for enhanced the portability of the system 3.

The data processing unit 22 can comprise a visual display unit for displaying the electric signal 11, the resonant frequency f_r, and/or the physiological dimension 4 of the abdominal region 5, et cetera. The data processing unit 22 can further comprise a memory unit for storing the generated electric signal 11, the determined resonant frequency f_r, and/or the physiological dimensions 4 of the abdominal region 5, gathered over a certain time period, thereby facilitating the visualization of the variations of the same and for further analysis of the same.

A flowchart 200 of a method for the determination of the physiological movements the subject 5 is depicted in FIG 4. The flowchart 200 of FIG 5 is elucidated with reference to the preceding FIGS 1 to 4.

In step 210, the sensor 9 is affixed to the part 5 of the subject 2 using the attaching means 10 comprised in the sensor module 6. Thereafter, the sensor module 6 is operably coupled to the frequency processing unit 7. Furthermore, necessary electric connections can be made such that the power supply unit 8 is configured to provide the electric power required for the functioning of the sensor module 6 and the frequency processing unit 7.

In step 220, the electric signal 11 corresponding to the dimension 12 of the sensor 9, which in turn corresponds to the physiological dimension 4 of the part 5 of the subject 2, is generated. The electric signal 11 generated thereof is provided to the frequency processing unit 7.

In step 230, the resonant frequency f_r of the electric signal 11 is determined by the frequency processing unit 7.

Furthermore, in a subsequent step 240, the dimension 12 of the sensor 9, which corresponds to the resonant frequency f_r of the electric signal 11, is determined. The dimension 12 of the sensor 9 can be determined from the resonant frequency f_r of the electric signal 11 based on the aforementioned

equation .

In step 250, the physiological dimension 4 of the part 5 of the subject 2, which corresponds to the dimension 12 of the sensor 9, is determined. The determination physiological dimension 4 can be in accordance with either the

aforementioned calibration relationship or in accordance with the aforementioned lookup table comprised in the processing module 15.

The steps 220, 230, 240 and 250 can be repeated for a certain interval of time for monitoring of the temporal variations of the physiological dimension 4 of the part 5 of the subject 2. Herein, the temporal variations of the physiological

dimension 4 of the part 5 of the subject 2 correspond to the physiological movements of the part 5 of the subject 2. Thus, the physiological movements can be analysed for assessing the healthiness of the subject 2.

An exemplary graph 23 depicting the temporal variations of the dimensions 12 of the sensor 9 is depicted in FIG 5a.

Another exemplary graph 26 depicting the temporal variations of the resonant frequency f_r of the sensor 9, determined from the corresponding temporal variations of the dimensions 12 of the sensor 9, is depicted in FIG 5b. Another exemplary graph 28 depicting the temporal variations of the physiological dimensions 4 of the part 5 of the subject 2, determined from the corresponding temporal variations of the resonant

frequency f_r of the sensor 9, is depicted in FIG 5c.

The aforementioned graphs 23,26,28 depict the temporal variations of the aforementioned parameters (viz. the

dimension 12 of the sensor 9, the resonant frequency f_r of the sensor 9, and the physiological dimension 4 of the part 5 of the subject 2) corresponding to two respiration cycles of the subject 2. It may be noted herein that the abscissas 24 of the aforementioned graphs 23,26,28 denote time. The ordinate 25 of graph 23 depicts the dimension 12 of the sensor 9, the ordinate 27 of graph 26 depicts resonant frequency f_r of the sensor 9, and the ordinate 29 of graph 28 depicts the physiological dimension 4 of the part 5 of the subject 2.

Though the invention has been described herein with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various examples of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the present invention.

Claims

Patent claims

1. A system (3) for determining a physiological dimension (4) of a part (5) of a subject (2), the system (3) comprising: - a sensor module (6) for detecting the physiological

dimension (4) of the part (5) of the subject (2) and for generating electric signals (11) of distinct frequencies f corresponding to distinct physiological dimensions (4) of the part (5) of the subject (2), wherein each distinct frequency f of the electric signal (11) corresponds

uniquely to a distinct physiological dimension (4) of the part (5) of the subject (2), and

- a frequency processing unit (7) for determining the

physiological dimension (4) of the part (5) of the subject (2) from the frequency f of the electric signal (11), wherein the frequency processing unit (7) is operably coupled to the sensor module (6) for receiving the electric signal (11).

2. The system (3) according to claim 1, wherein the sensor module (6) comprises a sensor (9), wherein a dimension (12) of the sensor (9) varies in accordance with a variation of the physiological dimension (4) of the part (5) of the subj ect (2 ) .

3. The system (3) according to claim 2, wherein the frequency f of the generated electric signal (11) is dependent on the dimension (12) of the sensor (9) .

4. The system (3) according to claim 2 or claim 3, wherein the frequency f of the generated electric signal (11) is the resonant frequency f_r of the sensor (9) .

5. The system (3) according to claim 4, wherein the resonant frequency f_r of the sensor (9) is inversely proportional to the dimension (12) of the sensor (9) .

6. The system (3) according to any of the claims 2 to 5, wherein the dimension (12) of the sensor (9) is the length of the sensor ( 9) .

7. The system (3) according to any of the claims 2 to 6, wherein the sensor (9) comprises an antenna, wherein the antenna (9) undergoes dimensional variations based on the variation of the physiological dimension (4) of the part (5) of the subject (2) .

8. The system (3) according to claim 7, wherein the antenna (9) is capable of operating in the Ultra High Frequency range .

9. The system (3) according to claim 7 or claim 8, wherein the antenna (9) is a fluidic antenna.

10. The system (3) according to claim 7 or claim 8, wherein the antenna (9) is a textile antenna.

11. The system (3) according to any of the claims 1 to 10, wherein the frequency processing unit (7) comprises:

- a frequency demodulator module (14) for demodulating the generated electric signal (11) for determining the

frequency f of the electric signal (11), and

- a processing module (15) for determining the physiological dimension (4) of the part (5) of the subject (2) from the frequency f of the electric signal.

12. The system (3) according to any of the claims 2 to 11, further comprising:

- an attaching means (10) for attaching the sensor (9) to the part (5) of the subject (2) such that a change of

physiological dimension (4) of the part (5) of the subject (2) results in a change of dimension (12) of the sensor

(9) .

13. The system (3) according to any of the claims 1 to 12, further comprising:

- a power supply unit (8) for providing electric power to at least one of the sensor module (6) and the frequency processing unit (7) .

14. The system (3) according to any of the claims 1 to 13, wherein the frequency processing unit (7) is integrated into the sensor module (6),

the system (3) further comprising:

- a transmitting means (21) for providing at least one of the resonant frequency f_r of the electric signal (11) and the physiological dimension (4) of the part (5) of the subject (2) to a data processing unit (22) for visualizing at least one of the electric signal (11), the resonant frequency f_r, and the physiological dimension (4) of the part (5) of the subj ect (2 ) .

15. The system (3) according to any of the claims 1 to 14, wherein the system (3) is a respiration rate determination system, wherein the sensor module (6) is configured to detect variations of the physiological dimension (4) of an abdominal region (5) of the subject (2) during a respiration cycle of the subj ect (2 ) .

16. A method for determining a physiological dimension (4) of a part (5) of a subject (2), the method comprising:

- a step (230) of determining a frequency f of an electric signal (11) generated by a sensor (9), wherein the sensor (9) is affixed to the part (5) of the subject (2), and wherein the sensor (9) generates an electric signal (11) of a distinct frequency f corresponding to a distinct

physiological dimension (4) of the part (5) of the subject (2) ,

- a step (250) of determining the physiological dimension (4) of the part (5) of the subject (2) from the frequency f of the electric signal (11), wherein the physiological dimension (4) corresponds to the frequency f of the

generated electric signal (11).

17. The method according to claim 16, wherein the step (230) of determining the frequency f of the electric signal (11) comprises :

- demodulating the electric signal (11) for determining the frequency f of the electric signal (11), and

- processing the determined frequency f of the electric signal (11) for determining the dimension (12) of the sensor (9) corresponding to the determined frequency f of the electric signal (11) .

18. The method according to claim 15 or claim 16, wherein the step (250) of determining the physiological dimension (4) of the part (5) of the subject (2) comprises:

- processing the determined dimension (12) of the sensor (9) based on a calibration relationship, wherein the

calibration relationship defines a relation between the dimension (12) of the sensor (9) and the physiological dimension (4) of the part (5) of the subject (2) .