Recently, the radiofrequency ablation catheter is widely used in the treatment of atrial fibrillation. Radiofrequency catheter tip is inserted through femoral vein puncture and pushed to the heart cavity. The radio frequency energy is applied to the ablation lesion on the inner wall of the heart, and then the heart cells die to achieve the aim of treatment[1]. During the treatment, however, the patients need repeated ablation because of the ineffective ablation, and the complications may occur. Continuous pulmonary vein lesion and isolation of wall is very important to increase the success of surgery [2]. Research [3] shows that the contact force between catheter tip and the tissue of inner heart is a key factor influencing the lesion size.
In order to monitor the contact force, many force sensors have been studied. Fukuda [4] used semiconductor strain gage outside of the catheter to monitor the contact force. Peirs [5] monitored the contact force by optical technology.
The disadvantages of the current sensors are using special expensive signal detecting and analyzing instrument, such as Endosense (SMART touch), which will increase the cost tremendously. For clinical application, it is necessary to develop a low cost sensor with enough accuracy which can also be used in the catheter for contact force measurement.
This paper focuses on designing a novel force-voltage transferring sensor. The sensor consists of a Ni-Ti alloy tube and several strain gages. With the compact design of a spiral structure, it can reduce the overall cost while keeping a good performance at the same time. The price of SMART touch catheter is 4, 348 dollars. The proposed design will be as much as 20–30 percent below SMART’s price.
