Wearable device and a method for determining induced voltage exposure of a human body to RF radiation and static electricity variation

Abstract

A wearable device and a method are disclosed for determining induced voltage exposure of a human body to low voltage fluctuations or induced static electricity variation on human body. The wearable device includes conductive elements which form at least part of an antenna and comprises an RF-to-DC converter connected to the conductive elements of the wearable device for harvesting RF energy and induced static electricity variation at the input in the form of an AC voltage (V.sub.in), while the RF-to-DC converter provides a DC voltage (V.sub.out) at the output. The wearable device also comprises a control unit connected to the output of the RF-to-DC converter to determine the induced voltage exposure of a device wearer's body.

Claims

1. A wearable device comprising conductive elements which form at least part of an antenna, an RF-to-DC converter connected to said conductive elements for harvesting RF energy and induced static electricity variation at the input in the form of an AC voltage (Vin), said RF-to-DC converter providing a DC voltage (Vout) at the output, and a control unit connected to the output of said RF-to-DC converter to determine the induced voltage exposure of a device wearer's body, wherein said conductive elements are configured to be in electrical contact with the wearer's body.

2. The wearable device according to claim 1, wherein said conductive elements are incorporated in a fabric.

3. The wearable device according to claim 1, wherein said RF-to-DC converter comprises a diode/capacitor multiplier circuit.

4. The wearable device according to claim 1, wherein said control unit is programmed to set a threshold voltage value to be compared with said DC voltage value V.sub.ow at the output of said RF-to-DC converter.

5. The wearable device according to claim 1, wherein said control unit and or said RF-to-DC converter are attached to, or incorporated in, the fabric.

6. The wearable device according to claim 2, wherein said control unit and or said RF-to-DC converter are attached to, or incorporated in, the fabric.

7. The wearable device according to claim 3, wherein said control unit and or said RF-to-DC converter are attached to, or incorporated in, the fabric.

8. The wearable device according to claim 4, wherein said control unit and or said RF-to-DC converter are attached to, or incorporated in, the fabric.

9. A method for determining the induced voltage exposure of a human's body wearing a wearable device according to claim 1, characterized by comprising the following steps: a) continuously harvesting RF energy or static electricity variation induced on the device wearer's body by means of conductive elements and the wearer's body acting as antennas, wherein said conductive elements are configured to be in electrical contact to the wearer's body; b) feeding an RF-to-DC converter with an AC voltage (V.sub.in) from the harvesting step a) to charge the capacitors (C2-C3) of said RF-to-DC converter in order to obtain a DC voltage (V.sub.out) at the output of said RF-to-DC converter; c) evaluating the amount of the induced voltage exposure on the basis of said DC voltage (V.sub.out) fed to the control unit of said wearable device.

10. The method according to claim 9, wherein said control unit is programmed to compare said DC voltage (V.sub.out) with a preset threshold voltage level and to increase the integer value of an internal counter when said DC voltage (V.sub.out) exceeds said preset threshold voltage level.

11. The method according to claim 10, wherein said capacitors (C2-C3) are discharged when said DC voltage (V.sub.out) exceeds said preset threshold voltage level.

12. The method according to claim 10, wherein said threshold voltage level is stored in said control unit as a digital value, and wherein said DC voltage (V.sub.out) is converted by said control unit from the analog to digital form before the comparison.

13. The method according to claim 9, wherein the integer value of the counter is periodically read in order to report the integer value stored in the counter and determine the induced voltage exposure on the wearer's body.

14. The method according to claim 13, wherein the counter value is reset after a reading of the stored integer value.

15. The method according to claim 10, wherein the integer value of the counter is periodically read in order to report the integer value stored in the counter and determine the induced voltage exposure on the wearer's body.

16. The method according to claim 11, wherein the integer value of the counter is periodically read in order to report the integer value stored in the counter and determine the induced voltage exposure on the wearer's body.

17. The method according to claim 12, wherein the integer value of the counter is periodically read in order to report the integer value stored in the counter and determine the induced voltage exposure on the wearer's body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other features and aspects of the present invention will become more apparent from the following description of the exemplary embodiments illustrated in the accompanying drawings, in which:

(2) FIG. 1 shows a schematic representation of a possible embodiment of the present invention; and

(3) FIG. 2 is a flowchart which shows some steps of the method according to the present invention.

DETAILED DESCRIPTION

(4) In particular, FIG. 1 schematically represents the detection and measurement of RF exposure on human's body wearing a device 10 including conductive elements which form at least part of an antenna and comprising a control unit 30.

(5) The wearable device, which will be referred in the following with the general reference number 10, could be for example, a part of a wrist watch 10a, a necklace 10b, an earring 10c, a shoe 10d, a shirt 10e, a part of trousers 10f such as jeans or the like, or actually anything having a good portion in contact with the wearer's body.

(6) The scheme of the electrical circuit shown on FIG. 1 represents a RF-to-DC converter 20, connected to the control unit 30, which is used to convert AC into DC. The control unit 30 receives the output voltage V.sub.out from the RF-to-DC converter 20 and transforms this analog value into a digital value.

(7) The RF-to-DC converter 20 and the control unit 30 are incorporated into the device 10 worn by an individual, for example by housing them in some parts of the wearable device such as straps, labels, buttons or the like.

(8) The electrical circuit of the RF-to-DC converter 20 comprises a diode/capacitor multiplier circuit having an input V.sub.in from the RF radiation and static electricity received in form of AC currents from the wearer's body and from the conductive elements of the wearable device, both acting as antennas. In particular, four diodes D1, D2, D3, D4 and four capacitors C1, C2. C3, C4 are used in this specific example; usage of more stages for voltage multiplication is also possible, though. The RF-to-DC converter 20 allows the harvested energy in form of AC currents to charge the capacitors C1-C4 and to provide a DC current output V.sub.out which is multiplied four times with respect to the input V.sub.in.

(9) In this specific example C1 and C4 are input capacitors for DC de-coupling. C2 and C3 are those actually charged/discharged to increment a counter. C1 and C4, usually of ceramic type with no polarity, are also charged and discharged continuously but they have a rather small capacity (e.g. nF) compared to C2 and C3. The latter are of electrolytic type, with polarity, and have a larger capacity (e.g. F) with respect to C1 and C4.

(10) As shown in FIG. 2, the capacitors C2-C3 are continuously charged by the harvested energy at step 100 and the output voltage V.sub.out from the RF-to-DC converter is fed to the control unit 30. The latter is programmed to convert the analog voltage value V.sub.out and continuously compare at step 200 the corresponding digital value with a threshold value stored into a memory of the control unit 30.

(11) If the value V.sub.out is smaller than the threshold value, the steps of charging the capacitors C2-C3 with harvested energy and feeding the output V.sub.out to the control unit 30 continues until V.sub.out does not exceed the threshold value. Once this condition is reached, capacitors C2-C3 are discharged and the integer value of the counter is increased at step 300 and the process restart again from step 100.

(12) While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. For example, even if the wearable device of the present invention has been disclosed as operating in a range of RF frequencies without specific limits, it should be understood that the principles of the present invention can be applied also to wearable devices operating at specific frequencies or small ranges of frequency.

(13) It should also be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims.