Wireless sensing system using sensing device with excitation element
At least some aspects of the present disclosure feature a mobile sensing system comprising a sensing device for measuring a thermal property of an object, comprising an RF circuit and an antenna electronically coupled to the RF circuit, a sensor electronically coupled to the RF circuit, and a thermal source thermally coupled to the sensor and electronically coupled to the RF circuit, a mobile device having a processor, an RF reader connected to or integrated with the mobile device, wherein the RF reader is configured to interrogate the sensing device; wherein the sensing device receives power when the RF reader interrogates the sensing device and provides at least a portion of the power to the thermal source.
1. A mobile sensing system, comprising:
a sensing device for measuring a thermal property of an object, comprising:
an RF circuit and an antenna electronically coupled to the RF circuit,
a sensor electronically coupled to the RF circuit, and
a thermal source thermally coupled to the sensor and electronically coupled to the RF circuit;
a thermal spreader having a first major surface and a second opposing major surface, such that when the sensing device is in use, the thermal spreader is in thermal contact with the object and the first major surface is proximate to the object, and the thermal source is disposed proximate to the second major surface, the thermal source generates a substantially uniform thermal flux on the first major surface of the thermal spreader;
a mobile device having a processor;
an RF reader connected to or integrated with the mobile device, wherein the RF reader is configured to interrogate the sensing device;
wherein the sensing device receives power when the RF reader interrogates the sensing device and provides at least a portion of the power to the thermal source,
wherein the sensor is configured to generate a series of sensing signals associated with temperature when the thermal source is powered,
wherein the sensing device is configured to transmit a series of data signals associated with the series of sensing signals via the antenna; and
wherein the RF reader receives the series of data signals and the processor is configured to determine the thermal property of the object using at least some of the series of data signals,
wherein the thermal spreader has a known thermal property, wherein the processor is further configured to determine the thermal property of the object using the known thermal property of the thermal spreader.
2. The mobile sensing system of claim 1 , wherein the sensing device further comprises a substrate, wherein the RF circuit and the antenna are disposed on the substrate.
3. The mobile sensing system of claim 1 , wherein the generated thermal flux is modified by the object when the sensing device is in use.
4. The mobile sensing system of claim 1 , wherein the sensing device further comprises:
an energy harvesting device electronically coupled to the RF circuit and configured to convert the power received by the sensing device to power in DC form.
5. The mobile sensing system of claim 4 , wherein the energy harvesting device comprises at least one of a bridge rectifier, a diode rectifier, a transistor rectifier, a voltage regulator and a current regulator.
6. The mobile sensing system of claim 1 , wherein the RF reader is configured to adjust interrogation power based on at least one of the series of data signals.