Hydrogen sensor

1. A gas sensor comprising:

a first electro-mechanical oscillator having a first frequency output controlled by a first mechanically resonant element;

a second electro-mechanical oscillator having a second frequency output controlled by a second mechanically resonant element, wherein the first mechanically resonant element exposed to a first environment that may contain a gas to be sensed, and the second mechanically resonant element exposed to a second environment that does not contain the gas to be sensed; and

circuitry for determining if the gas is present in the first environment by producing a sense signal with a frequency value that is a frequency difference between the first and second frequency outputs, wherein the gas is hydrogen and a presence of hydrogen in the first environment causes the first mechanically resonant element to vibrate at a higher frequency.

2. The gas sensor as recited in claim 1 wherein the determining circuit is a D flip-flop having its D input coupled to the first frequency output and its clock input coupled to the second frequency output so that a Q output of the D flip-flop produces the sense signal.

3. The gas sensor as recited in claim 1 , further comprising a means to activate both the first and second mechanically resonant elements of the first and second oscillators.

4. The gas sensor as recited in claim 1 , wherein the gas to be sensed is introduced to the first environment through a membrane preferentially permeable to the gas to be sensed.

5. The gas sensor as recited in claim 1 , further comprising a pulse counter having one input receiving the sense signal and another input receiving a reference frequency signal and an output generating a number of pulses proportional to a concentration of the gas in the first environment.

6. A gas sensor comprising:

means for activating a mechanical vibration to an oscillating rod thereby causing the mechanical vibration in the oscillating rod to occur at a natural oscillating frequency;

means for measuring a change in the natural oscillating frequency of the oscillating rod; and

means for outputting a sensing signal when the measuring means detects the change in the natural oscillating frequency in response to exposing the oscillating rod to an environment containing a particular gas, wherein the oscillating rod does not absorb gases when in the environment.

7. The gas sensor as recited in claim 6 , wherein the oscillating rod comprises a carbon nanotube.

8. The gas sensor as recited in claim 6 , wherein the oscillating rod is a tuning mechanism for an oscillator.

9. The gas sensor as recited in claim 8 , wherein the measuring means comprises a flip-flop circuit.

10. A gas sensor comprising:

a first oscillator having a first frequency output;

a second oscillator having a second frequency output, the first oscillator exposed to an environment that may contain a gas to be sensed, and the second oscillator exposed to an environment that does not contain the gas to be sensed; and

circuitry for determining if the gas is sensed by the first oscillator by producing a frequency signal that is a difference between the first and second frequency outputs, wherein the gas is hydrogen, and wherein a presence of hydrogen sensed by the first oscillator will cause it to vibrate at a higher frequency.

11. A gas sensor comprising:

a first oscillator having a first frequency output;

a second oscillator having a second frequency output, the first oscillator exposed to an environment that may contain a gas to be sensed, and the second oscillator exposed to an environment that does not contain the gas to be sensed;

circuitry for determining if the gas is sensed by the first oscillator by producing a frequency signal that is a difference between the first and second frequency outputs; and

a pulse counter having one input receiving the difference frequency signal and another input receiving a reference frequency signal to therefore output a number of pulses representing the sensing of the gas.