A method and system for calibrating a wireless sensor device are disclosed. In a first aspect, the method comprises determining a vertical calibration vector and determining a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes. In a second aspect, a wireless sensor device comprises a processor and a memory device coupled to the processor, wherein the memory device includes an application that, when executed by the processor, causes the processor to determine a vertical calibration vector and to determine a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes.

A method and system for calibrating a wireless sensor device are disclosed. In a first aspect, the method comprises determining a vertical calibration vector and determining a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes. In a second aspect, a wireless sensor device comprises a processor and a memory device coupled to the processor, wherein the memory device includes an application that, when executed by the processor, causes the processor to determine a vertical calibration vector and to determine a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes.

According to an embodiment, a time reference device is provided. In the embodiment, the time reference device, includes a corrodible element, wherein a corrosion of the corrodible element advances with advancing time, and a sensor configured for providing a sensor signal, the sensor signal depending on a physical property of the corrodible element; wherein the physical property of the corrodible element changes with a corrosion of the corrodible element and the physical property of the corrodible element is at least one of an electrical property, a magnetic property, and an optical property. A barrier may be provided for defining a permeability for a corrosive substance to the corrodible element.

According to an embodiment, a time reference device is provided. In the embodiment, the time reference device, includes a corrodible element, wherein a corrosion of the corrodible element advances with advancing time, and a sensor configured for providing a sensor signal, the sensor signal depending on a physical property of the corrodible element; wherein the physical property of the corrodible element changes with a corrosion of the corrodible element and the physical property of the corrodible element is at least one of an electrical property, a magnetic property, and an optical property. A barrier may be provided for defining a permeability for a corrosive substance to the corrodible element.

The timing device is a lifetime monitor for indicating when the usable lifetime of a product has ended or for indicating the timing for regular usage of a product. The timing device has a timing initiator, a power supply in the form of a membrane zinc air battery and a visual or audible indicator. The timing initiator is a tear-off air blocking membrane which lets in air when the tear off film is removed. The timing device is capable of indicating a predetermined passage of time which is substantially independent of ambient temperature.

The timing device is a lifetime monitor for indicating when the usable lifetime of a product has ended or for indicating the timing for regular usage of a product. The timing device has a timing initiator, a power supply in the form of a membrane zinc air battery and a visual or audible indicator. The timing initiator is a tear-off air blocking membrane which lets in air when the tear off film is removed. The timing device is capable of indicating a predetermined passage of time which is substantially independent of ambient temperature.

A timing device for indicating the passage of a duration of time is disclosed. The timing device and system, in accordance with the embodiments of the invention, comprise an electrochemical component which generates a visual and/or audio indication of the passage of time. The timing device further comprises a compensating element, such as a varistor, a thermistor and/or combinations thereof. The compensating element regulates the response of the device with respect to changes in temperature. The timing device is configured to indicate the passage of a single duration of time or comprises zones that are activated in a range of prescribed times and individually or collectively indicate the passage of time or the passage of a range of times.

A timing device for indicating the passage of a duration of time is disclosed. The timing device and system, in accordance with the embodiments of the invention, comprise an electrochemical component which generates a visual and/or audio indication of the passage of time. The timing device further comprises a compensating element, such as a varistor, a thermistor and/or combinations thereof. The compensating element regulates the response of the device with respect to changes in temperature. The timing device is configured to indicate the passage of a single duration of time or comprises zones that are activated in a range of prescribed times and individually or collectively indicate the passage of time or the passage of a range of times.

A method and system for calibrating a wireless sensor device are disclosed. In a first aspect, the method comprises determining a vertical calibration vector and determining a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes. In a second aspect, a wireless sensor device comprises a processor and a memory device coupled to the processor, wherein the memory device includes an application that, when executed by the processor, causes the processor to determine a vertical calibration vector and to determine a rotation matrix using the vertical calibration vector to line up native axes of the wireless sensor device with body axes.

A timing device comprises a sensing material and/or a component which is sensitive to the presence of an environmental attribute. The environmental attribute drives and speeds up or slows the timing device as the concentration of the attribute increases or decreases, respectively. Alternatively, the timing device is activated upon sensing the presence of the environmental attribute and indicates a total passage of time from exposure/activation of the timing device. Particularly, sensing materials of varying types are able to be used to indicate exposure to a variety of substances. For example, in some embodiments, the timing device comprises a sensing material which is sensitive to the presence of ultraviolet radiation. Alternatively, the sensing material is sensitive to other variables such as x-ray radiation and nuclear radiation. In further embodiments, the sensing material is sensitive to biological or physical contamination.