Catheter system

1. A catheter system comprising:

a catheter body, wherein at least a part of the catheter body is flexible;

at least one ring electrode; and

at least one strain gauge;

wherein the at least one ring electrode surrounds at least a portion of the flexible part of the catheter body;

wherein the at least one strain gauge is arranged in a proximity of the at least one ring electrode;

wherein the at least one strain gauge is configured to measure a deformation of the flexible part of the catheter body at a position in a proximity of the at least one ring electrode to indirectly detect a contact between the at least one ring electrode and tissue;

wherein the at least one strain gauge comprises a piezoresistive material comprising a carbon component and an elastomer component;

wherein the carbon component comprises carbon particles comprising macropores having a pore size between 50 nm and 1,000 nm measured by Hg porosimetry; and

wherein the piezoresistive material has an original state and the carbon particles allow the piezoresistive material to relax back to the original state when a force is removed.

2. The catheter system according to claim 1 , wherein the catheter system is a pig tail catheter.

3. The catheter system according to claim 1 , wherein the at least one strain gauge has a tubular shape and extends at least partially inside the catheter body.

4. The catheter system according to claim 1 , wherein the at least one ring electrode and the at least one strain gauge are arranged at a distal tip of the catheter body.

5. The catheter system according to claim 1 , wherein the at least one strain gauge is configured to output a change of electrical resistance depending on the deformation of the flexible part of the catheter body at the position and proximity of the at least one ring electrode, and wherein the catheter system further comprises a processing unit configured to calculate a contact force between the at least one ring electrode and tissue based on the change of electrical resistance.

6. The catheter system according to claim 5 , wherein the processing unit is spaced apart from the at least one ring electrode.

7. The catheter system according to claim 1 wherein the elastomer component comprises polymeric chains, and wherein at least some of the macropores in the carbon particles are infiltrated by polymeric chains to form a piezoresistive interconnection between the carbon particles.

8. The catheter system according to claim 7 , wherein the polymeric chains are configured to rearrange when the piezoresistive material is subjected to the force so that electrical paths form between the carbon particles to decrease an electrical resistance of the piezoresistive material.

9. The catheter system according to claim 1 , wherein the carbon particles are highly porous with a total pore volume between 0.7 and 3.5 cm 3 /g measured by Hg porosimetry.

10. The catheter system according to claim 1 , wherein the macropores in the carbon particles have a macropore volume between 0.6 and 2.4 cm 3 /g measured by Hg porosimetry.

11. The catheter system according to claim 1 , wherein the carbon particles further comprise mesopores with a pore size between 2 and 50 nm and a mesopore volume between 0.05 and 0.2 cm 3 /g measured by Hg porosimetry.

12. The catheter system according to claim 1 , wherein the carbon component is graphitized to a graphitization degree between 60 and 80%.

13. The catheter system according to claim 1 , wherein the carbon particles comprise no micropores with a pore size smaller than 2 nm measured based on the Brunauer-Emmet-Teller method.

14. The catheter system according to claim 1 , further configured for one or more of sensing force, ablation of tissue, stimulation of tissue, delivery of a drug and insertion of an implant.

15. The catheter system according to claim 1 , further configured in a pig tail catheter device, a balloon catheter device, a renal ablation device, a delivery catheter, a cochlea implant, a cardiac resynchronization device, a pacemaker, a neuro stimulation device, a fluid pressure monitoring device, and/or a stent.

16. The catheter system according to claim 1 , wherein the catheter body forms a helical shape configured to surround an area of tissue, wherein the catheter system comprises at least a first and a second strain gauge and at least a first and a second ring electrode, wherein the first strain gauge is arranged in proximity of the first ring electrode and the second strain gauge is arranged in proximity of the second ring electrode, wherein the first strain gauge is configured to measure the deformation of the flexible part of the catheter body at a position and in proximity of the first ring electrode to indirectly detect a contact between the first ring electrode and the tissue, and wherein the second ring electrode is configured to measure the deformation of the flexible part of the catheter body at a position and in proximity of the second ring electrode to indirectly detect contact between the second ring electrode and the tissue.

17. The catheter system according to claim 1 , comprising several strain gauges and several ring electrodes.

18. The catheter system according to claim 1 , wherein the carbon particles have a particle size distribution d50 between 1 μm 100 μm, as measured by laser diffraction.

19. The catheter system according to claim 1 , wherein the force is a force between 0.02 N and 1 N.