Wireless sensor with multiple sensing options

1. A wireless sensor comprises:

a radio frequency (RF) front end that includes:

an antenna for transceiving data via an RF signal; and

a tuning circuit, wherein the tuning circuit adjust a resonant frequency of the RF front end to be approximately equal to a resonant frequency of the RF signal;

a sensing integrated circuit (IC) that includes a power supply, a first power supply connection, and a second power supply connection, wherein the power supply generates a voltage from the RF signal; and

a power supply impedance altering element coupled to the first and second power supply connections, wherein the power supply impedance altering element detects a condition of an item, wherein the sensing IC is operable to:

detect an impedance change of the power supply based on an effect of the power supply impedance altering element;

convert the impedance change into a digital value that is representative of the condition of the item; and

output, via the antenna, the digital value or a representation of the condition of the item.

2. The wireless sensor of claim 1 , wherein the power supply impedance altering element comprises:

a sensing element that includes a first metallic trace coupled to the first power supply connection and a second metallic trace coupled to the second power supply connection, wherein the sensing element is operable to detect the presence or absence of moisture.

3. The wireless sensor of claim 2 , wherein the sensing element further comprises:

the first and second metallic traces are approximately parallel to each other and have a length, wherein a first end of the first metallic trace is coupled to the first power supply connection and a first end of the second metallic trace is coupled to the second power supply connection; and

a moisture pad mounted at a second end of the first and second metallic traces for capturing at least one of moisture and an electrolyte content of a fluid.

4. The wireless sensor of claim 1 , wherein the power supply impedance altering element comprises:

a potentiometer, wherein the item is a shaft of a rotating part, wherein, as the shaft is rotated, the potentiometer changes impedance of the power supply.

5. The wireless sensor of claim 1 , wherein the sensing IC is further operable to:

generate a reference digital value for a known impedance of the power supply that corresponds to a known condition of the item;

detect an amount of the impedance change of the power supply based on the effect of the power supply impedance altering element; and

generate the digital value based on the amount of impedance change and the known impedance of the power supply for the known condition of the item.

6. The wireless sensor of claim 1 further comprises:

a sensing element for sensing a second condition of a second item, wherein, as the second condition changes, the sensing element changes an input impedance of the wireless sensor, wherein the sensing IC is operable to:

receive a sensed condition of the second item from the sensing element;

determine the input impedance of the wireless sensor based on the sensed condition;

convert the input impedance into a second digital value that is representative of the second condition of the second item; and

output, via the antenna, the second digital value or a representation of the second condition of the second item.

7. The wireless sensor of claim 6 , wherein the second condition of the second item comprises one or more:

a change in the second condition with respect to a reference condition; and

a measure of the second condition.

8. The wireless sensor of claim 6 , wherein the second condition of the item comprises one or more of:

temperature;

moisture;

pressure;

concentration level of the item; and

presence or absence detection of the item.