Pressure sensor catheter based on Fiber Tip Fabry-Pérot-Interferometer and Fiber Bragg Grating for temperature compensation

This paper introduces a pressure sensor catheter with two different measurement principles. A Fabry-Perot- Interferometer at the fiber tip is formed by a reflective multilayer membrane of a pressure sensor chip. The cavity provides absolute pressure sensing. 20 millimeter before the fiber tip a Fiber Bragg Grating is integrated for additional temperature sensing. The sensing components are completely coated with a silicone mantle of 2 mm diameter. The signal evaluation is both done with a Fiber Bragg Grating interrogation device. First, mechanical structure aspects of the manufactured fiber-optic hybrid sensor as well as the sensing principle is described. Then, experimental results, including quantification and separation of pressure and temperature sensitivity are presented. Out of these characteristics the possibility for absolute pressure sensing with temperature compensation for the application as a pressure sensor catheter is confirmed.

[Prediction of overactive bladder treatment outcome by using long-term urodynamics]

In Germany, overactive bladder (OAB) syndrome affects around 6.5 million people over the age of 40. The primary treatment consists of anticholinergics or beta-3-receptor agonists. After an anticholinergic treatment period of around 4 months, compliance is around 40%, which is probably due a larger proportion of nonresponders. One condition of an efficient medication treatment is the presence of detrusor overactivity (DO). However, the detection rate of DO during standard urodynamics is very low. The primary goal in the future is to target OAB treatment by detection of DO. Using the Wille Capsule (WiCa) in an in vitro model, DO could be detected over a time period of 72 h, which would ensure a higher compliance to the OAB treatment in a positive way.

Catheterless long-term ambulatory urodynamic measurement using a novel three-device system

Aims

Long-term urodynamics are required because bladder-emptying disorders are often not clearly revealed by conventional urodynamics. Patients with severe clinical overactive bladder symptoms, for instance, often show normal results. This may be due to the short evaluation time and psychological factors that complicate conventional urodynamics. This study aimed to develop an ambulatory three-component urodynamic measurement system that is easy to operate, registers urodynamic parameters for several days, and has no negative impact on the patient.

Methods

We developed an intravesical capsule combined with a hand-held device to register voiding desire and micturition, and an alarm pad device that detects urine loss. Recently, the intravesical capsule and its proven function were detailed in the literature. Here, we present detailed in vitro results using a female bladder model. The flexible capsule was C-shaped to minimize the risk of expulsion from the bladder during micturition. Results of biocompatibility evaluation of the intravesical capsule, which is called Wille Capsule (WiCa) are described.

Results

The WiCa with an oval nose and a maximum outer diameter of 5.5 mm was easily inserted through a 25-French cystoscope. Removing the WiCa by grasping the nose using the female model with bladder was easily conducted. Expulsion of the WiCa during voiding was avoided through a novel C-shaped device design. Based on in vitro cytotoxicity studies, the capsule is a promising and safe device.

Conclusion

Our novel system is an innovative minimally-invasive tool for accurate long-term urodynamic measurement, and does not require inserting a transurethral catheter.

Coupled tangential-axial resonant modes of piezoelectric hollow cylinders and their application in ultrasonic motors

This paper describes a tangential-axial eigen-mode of a piezoelectric hollow cylinder. A new type of piezoelectric ultrasonic motor using this oscillation mode has been developed. The motor is a traveling-wave-type motor. The stator of such a motor consists of a solid piezoelectric hollow cylinder, which, excited in the tangential-axial resonant mode by a three-phase electrical signal, will exhibit elliptical displacement and transfer rotation to the rotor. The behavior of the stator has been simulated with finite element method (FEM) software. The simulation results have been checked with single-point contact measurements on the surface of the ultrasonic motors. The paper closes with the introduction of new ultrasonic motors based on this oscillation mode.