Modeling the Nonlinear Properties of Ferroelectric Materials in Ceramic Capacitors for the Implementation of Sensor Functionalities in Implantable Electronics

For several years, the requirements on miniaturization of electronic implants with application in functional electrostimulation have been increasing, while functionality and reliability should not be impaired. One solution concept is to use neither active electronic components nor sensors or batteries. Instead, the functionalities are ensured by the use of intrinsic nonlinear properties of the already used components and energy is transferred by inductive coupling. In this paper, ceramic capacitors are investigated as a first step towards exploiting the nonlinear characteristics of ferroelectric materials. The ceramic capacitors are characterized by simulation and measurements. The modeling is carried out in Mathcad Prime 3.1 and ANSYS 2019 R2 Simplorer and different solvers are compared for exemplary calculations. Finally, a measurement setup is realized to validate the models. Calculations show that the trapezoid method with a number of 500 k points in the given solution interval is best suited for ANSYS. In Mathcad, the Adams, Bulirsch–Stoer, Backward Differentiation Formula, Radau5, and fourth order Runge–Kutta methods with an adaptive step width and a resolution of 50 k points are the most suitable. The nonlinear properties of ferroelectric materials in ceramic capacitors modeled with these methods using ANSYS and Mathcad show small and equal deviation from the measurements.

A Measurement Setup and Automated Calculation Method to Determine the Charge Injection Capacity of Implantable Microelectrodes

The design of safe stimulation protocols for functional electrostimulation requires knowledge of the “maximum reversible charge injection capacity” of the implantable microelectrodes. One of the main difficulties encountered in characterizing such microelectrodes is the calculation of the access voltage Va. This paper proposes a method to calculate Va that does not require prior knowledge of the overpotential terms and of the electrolyte (or excitable tissue) resistance, which is an advantage for in vivo electrochemical characterization of microelectrodes. To validate this method, we compare the calculated results with those obtained from conventional methods for characterizing three flexible platinum microelectrodes by cyclic voltammetry and voltage transient measurements. This paper presents the experimental setup, the required instrumentation, and the signal processing.

MOTENA GIBLJIVOST GLASILK - DIAGNOSTIČNI POSTOPKI IN ZDRAVLJENJE 2. del

Paresis or paralysis of one or both vocal cords affects phonation, swallowing and breathing. The major cause for reduced mobility or even immobility is innervation damage, less often mechanical disorder.The main procedures in the diagnostics of disordered vocal fold mobility are indirect laryngoscopy and videoendostroboscopy. Different imaging techniques (especially computerized tomography) are of great value in searching for a cause of the impaired mobility.In unilateral vocal fold immobility, the treatment is focused on the improvement of voice quality and the prevention of aspiration during swallowing. In bilateral paralysis, it is crucial to find a balance between effective breathing and sufficient voice quality. The treatment of unilateral paralysis is started with voice therapy and swallowing rehabilitation. If these procedures are not enough surgical treatment for the medialization of the paralyzed vocal fold is applied. In the case of breathing difficulties in bilateral vocal fold immobility there is a possibility of surgical lateralization of one or both folds or a surgical excision of a part or the entire vocal fold. Surgical reinnervation, functional electrostimulation of certain laryngeal muscles and gene therapy are developing treatment modalities.