Adaptive Electrical Stimulation to Improve In-Vitro Cell Growth

AbstractAn adaptive system is used to stimulate electrically (In-Vitro) muscle vagina cells and epithelial rabbit bladder cells with external electrical stimulation ES. Waveform stimulation is synthesized from both: A specific known action potential or by a set of independent ionic potentials conforming a multi output system. Each ionic potential is the output of a set of FIR filters in which the coefficient adaptation is carried out by using a time varying step size normalized LMS (NLSM) algorithm. The adaptive system output stimulates in-vitro culture cells emulating biological neurotransmitters action. Electrical stimulation (ES) shows that cells under test grow faster than non-stimulated ones, observing bigger cell viability in stimulated cells than non stimulated. The objective of the experiment is to analyze the effect of external electrical stimulation ES on confluence and cell viability in culture cells by MTT (3-[4,5-Dimethylthiazol-2-Yl]-2,5-diphenyl-tetrazolium bromide) assays [A]

Study of the Effect of Distance and Misalignment between Magnetically Coupled Coils for Wireless Power Transfer in Intraocular Pressure Measurement

An analysis of the effect of distance and alignment between two magnetically coupled coils for wireless power transfer in intraocular pressure measurement is presented. For measurement purposes, a system was fabricated consisting of an external device, which is a Maxwell-Wien bridge circuit variation, in charge of transferring energy to a biomedical implant and reading data from it. The biomedical implant is an RLC tank circuit, encapsulated by a polyimide coating. Power transfer was done by magnetic induction coupling method, by placing one of the inductors of the Maxwell-Wien bridge circuit and the inductor of the implant in close proximity. The Maxwell-Wien bridge circuit was biased with a 10 MHz sinusoidal signal. The analysis presented in this paper proves that wireless transmission of power for intraocular pressure measurement is feasible with the measurement system proposed. In order to have a proper inductive coupling link, special care must be taken when placing the two coils in proximity to avoid misalignment between them

Integrated Bidirectional Inductive-Array Design for Power Transfer in Implantable BioMEMS

This work presents a novel design of a bidirectional Inductive Power Transfer (IPT) system capable of continuous monitoring of cardiac pressure. The proposed system results from a robust electromagnetic coupling between an external reading coil and an implanted two-level (3D approach) inductor array. In this design, each coupling module follows a 13.56 MHz operating frequency, where both passive RCL networks are near field tuned. Among our main results, we obtained a Power Transfer Efficiency (PTE) of 94.1% across the 3.5 cm-thick composed biological tissue whereas the implanted coil array is about 50% of its conventional size. Since the resulting PTE efficiency is 40% higher, based on the optimized L and Q parameters, this novel approach could be used in other medical applications. This IPT system design is based on a low-cost thin film fabrication technology

Design of a Fully Integrated Inductive Coupling System: A Discrete Approach Towards Sensing Ventricular Pressure

In this paper, an alternative strategy for the design of a bidirectional inductive power transfer (IPT) module, intended for the continuous monitoring of cardiac pressure, is presented. This new integrated implantable medical device (IMD) was designed including a precise ventricular pressure sensor, where the available implanting room is restricted to a 1.8 × 1.8 cm2 area. This work considers a robust magnetic coupling between an external reading coil and the implantable module: a three-dimensional inductor and a touch mode capacitive pressure sensor (TMCPS) set. In this approach, the coupling modules were modelled as RCL circuits tuned at a 13.56 MHz frequency. The analytical design was validated by means of Comsol Multiphysics, CoventorWare, and ANSYS HFSS software tools. A power transmission efficiency (PTE) of 94% was achieved through a 3.5 cm-thick biological tissue, based on high magnitudes for the inductance (L) and quality factor (Q) components. A specific absorption rate (SAR) of less than 1.6 W/Kg was attained, which suggests that this IPT system can be implemented in a safe way, according to IEEE C95.1 safety guidelines. The set of inductor and capacitor integrated arrays were designed over a very thin polyimide film, where the 3D coil was 18 mm in diameter and approximately 50% reduced in size, considering any conventional counterpart. Finally, this new approach for the IMD was under development using low-cost thin film manufacturing technologies for flexible electronics. Meanwhile, as an alternative test, this novel system was fabricated using a discrete printed circuit board (PCB) approach, where preliminary electromagnetic characterization demonstrates the viability of this bidirectional IPT design

Design and Simulation of an Integrated Wireless Capacitive Sensors Array for Measuring Ventricular Pressure

This paper reports the novel design of a touch mode capacitive pressure sensor (TMCPS) system with a wireless approach for a full-range continuous monitoring of ventricular pressure. The system consists of two modules: an implantable set and an external reading device. The implantable set, restricted to a 2 × 2 cm2 area, consists of a TMCPS array connected with a dual-layer coil, for making a reliable resonant circuit for communication with the external device. The capacitive array is modelled considering the small deflection regime for achieving a dynamic and full 5–300 mmHg pressure range. In this design, the two inductive-coupled modules are calculated considering proper electromagnetic alignment, based on two planar coils and considering the following: 13.56 MHz frequency to avoid tissue damage and three types of biological tissue as core (skin, fat and muscle). The system was validated with the Comsol Multiphysics and CoventorWare softwares; showing a 90% power transmission efficiency at a 3.5 cm distance between coils. The implantable module includes aluminum- and polyimide-based devices, which allows ergonomic, robust, reproducible, and technologically feasible integrated sensors. In addition, the module shows a simplified and low cost design approach based on PolyMEMS INAOE® technology, featured by low-temperature processing

Study of Oxygen Vacancies in TiO2 Nanostructures and Their Relationship with Photocatalytic Activity

In this research work, we present the synthesis and characterization of four different TiO2 structures, such as nanotubes, nanocavities, nanosheets assembled on nanocavities and nanobowls assembled on nanocavities, prepared by electrochemical anodization using organic electrolytes. After synthesis, the structures were thermally annealed to pass from the amorphous phase to the anatase phase, which is one of the most important crystalline structures of TiO2 due to its high photocatalytic activity and stability. The unique morphology and topography were studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The elemental composition was determined by energy-dispersive X-ray spectroscopy (EDS). The anatase phase was verified by Raman microscopy and X-ray diffraction (XRD), the band gap energy was calculated by the Kubelka–Munk function, and the main defect states that generate the emission, as well as their lifetime, were determined by photoluminescence spectroscopy and time response photoluminescence (TRPL), respectively. The TiO2 nanomaterials were tested as catalysts in the photodegradation of a solution of methylene blue using a UV lamp at room temperature. The results showed complex morphologies and different surface roughness areas of these nanomaterials. Furthermore, a relationship between defect states, band gap energy, and photocatalytic activity was established. We found that the catalytic activity was improved as an effect of geometric parameters and oxygen vacancies