Overlaid multi sensor radio frequency (RF) electrode system to measure tissue compression

1. A tissue compression sensor system comprising:

an RF electrode positioned on an end-effector;

a first electrical contact positioned on one of an anvil or a channel frame of the end-effector;

a first filter communicatively coupled to the first electrical contact;

a second electrical contact positioned on another of the anvil or the channel frame of the end-effector;

a second filter communicatively coupled to the second electrical contact; and

a multiplexer configured to overlay two or more RF tissue monitoring signals and transmitting the overlaid two or more RF tissue monitoring signals to the end-effector, and

a controller coupled to the multiplexer,

wherein a frequency of each of the two or more RF tissue monitoring signals is in a range of 100 kHz to 20 MHz, and

wherein each of the two or more RF tissue monitoring signals is at a different frequency,

wherein the controller is configured to simultaneously measure a first impedance at a first frequency and a second impedance at a second frequency using the RF electrode, and

wherein the controller is further configured to determine a vertical tissue compression based on the first impedance and a lateral tissue compression based on the second impedance.

2. The tissue compression sensor system of claim 1 , wherein the first and second electrical contacts lead to a common return path.

3. The tissue compression sensor system of claim 1 , wherein the two or more RF tissue monitoring signals are transmitted down a single power side of the end-effector.

4. The tissue compression sensor system of claim 1 , further comprising:

an impedance calculator in communication with the first and second filters.

5. The tissue compression sensor system of claim 1 , further comprising:

a frequency generator configured to generate the two or more RF tissue monitoring signals.

6. The tissue compression sensor system of claim 1 , wherein the RF electrode is positioned on a staple cartridge of the end-effector.

7. The tissue compression sensor system of claim 1 , wherein the RF electrode comprises multiple RF electrodes positioned on the end-effector at discrete points.

8. The tissue compression sensor system of claim 1 , wherein the RF electrode comprises multiple RF electrodes positioned on the end-effector in multiple zones.

9. A method for sensing tissue compression, the method comprising:

clamping tissue between two jaws of an end-effector, the jaws of the end-effector comprising an anvil, a channel frame, and an RF electrode for measuring impedance of the tissue,

overlaying, by a controller, two or more RF tissue monitoring signals on a multiplexer and transmitting the overlaid RF tissue monitoring signals to the end-effector;

returning the overlaid two or more RF tissue monitoring signals on a common return path via electrical contacts on at least one of the anvil or the channel frame of the end-effector; and

filtering, by two or more filters, the overlaid two or more RF tissue monitoring signals prior to joining the RF tissue monitoring signals on the common return path,

wherein a frequency of each of the two or more RF tissue monitoring signals is in a range of 100 kHz to 20 MHz, wherein each of the two or more RF tissue monitoring signals is at a different frequency,

simultaneously measuring a first impedance at a first frequency and a second impedance at a second frequency using the RF electrode,

determining a vertical tissue compression based on the first impedance, and

determining a lateral tissue compression based on the second impedance.

10. The method of claim 9 , further comprising:

calculating an impedance associated with a tissue compressed by the end-effector based on at least one of the two or more RF tissue monitoring signals.

11. The method of claim 10 , wherein a proximal tissue compression is calculated based on one of the RF tissue monitoring signals and a distal tissue compression is calculated based on another of the RF tissue monitoring signals.

12. The method of claim 9 , wherein the two or more RF tissue monitoring signals are overlaid via a multiplexer.

13. The method of claim 9 , wherein the two or more RF tissue monitoring signals are generated by a frequency generator outside the end-effector.

14. The method of claim 13 , wherein the frequency generator is located on a circuit board of a shaft or a handle of an endocutter.

15. The method of claim 9 , wherein two or more filters are used to filter the two or more RF tissue monitoring signals prior to joining the common return path to differentiate separate tissue impedances represented by the two or more RF tissue monitoring signals.