F. Ravariu

Glucose biofuels properties in the bloodstream, in conjunction with the beta cell electro-physiology

The modern medicine cannot be conceived without the latest news in engineering technology. One of the challenges is related to the novel energy source inside the human body that can be useful for implantable devices, as pacemakers or in vivo insulin micropumps or biosensors.

The modeling of a sensor for the human blood pressure

Blood pressure detection requires both sound detection and pressure measurements. Piezoelectric materials fulfill both aims. Starting from a previous work, a pressure sensor based on a SOI transistor with a piezoelectric layer, was adapted for the blood pressure domain. The ANSYS simulations provide the mechanical stress in the structure. The ATLAS software simulates the electrical behavior. This paper offers a modeling of the sensor and consequently design guidelines.

From Ψ-MOSFET with silicon on oxide to Ψ-MOSFET with silicon carbide on nitride

The Ψ-MOSFET is a device used in SOI electrical characterization. The aim of this paper was to establish a comparison between these transistors made in four variants: (1) with silicon film on buried oxide; (2) with silicon carbide film on buried oxide; (3) with silicon film on buried nitride; and (4) with silicon carbide film on buried nitride. ATLAS software simulated these structures. Besides this virtual experiment, a more complex model for the flat-band voltage is provided.

A designing roule for a pressure sensor with PZT layer

In the pressure sensors domain, the SOI structures bring some advantages: electrical insulation, high temperature sensors, an excellent etch stop layer (buried oxide), compatibility with microelectronic technology, lowering in thermal noise. The goal of this paper is to highlight a pressure sensor based on a coupling between piezoelectric effect in PZT and an /spl Psi/-MOSFET. The analytical models, that will be presented, stand for a useful tool at a first iteration of the sensor designing.

More Accurate Models Of The Interfaces Oxide Charge From The Ultra‐Thin SOI Films

An inherent SOI device dedicated for the in situ electrical characterization of wafers is the pseudo‐MOS transistor that easily provides a key parameter: Flat‐Band Voltage, VFB. Usual models for this voltage were established for SOI structures with 0,2μm…2μm film thickness and 0,4…100μm oxide thickness. The classical models of VFB, deduced for micronic sizes, present some deficiencies in the nanodevice area. An interface charge about 1012e/cm2 in micronic sizes means 1e/100nm2 equivalent with one electron per device area in the nano‐domain. This paper analyses the flat‐band voltage modeling, due to the consequences of the down‐scaling of the SOI wafers.

The influence of buried insulator type and film thickness on threshold voltage of a partially and fully depleted SOI-MOSFET

Nowadays SOI technologies represent a milestone in the fabrication of devices and integrated systems on thin films. The analytical models for the threshold voltage are useful for many SOI devices. Our analysis has focused on partially and fully depleted films, achieved on insulators like oxide, nitride or oxinitride. This paper gives a simple and accurate estimation of the threshold voltage. The results were in a good agreement both with PISCES numerical simulations and with experimental data.

From Experimental Investigations with Laser Bio-Photometry to Statistical Models Applied for the Normal and Pathological Tissue

The aim of this paper is to implement a mathematical predictor algorithm to estimate the health-state evolution versus some measurable index. A relatively new medical tool was used for patients monitoring: the laser close infrared spectrum (850nm) for in vivo interaction with the human tissues. As a main statistic variable was considered the average reflection coefficient, ARC. The determined ARC coefficient in the intact tissues is an index of the health-state, having a range between 55,7 to 68 mW + 2,1 mW, being very stable in time. The determined average reflection coefficient in the pathologically modified tissues constantly decreases from 58 up to 42 mW + 3,4 mW and varies in time according to the evolution of the pathological process. However, the overlap for the ARC ranges occurs among diseases that induce uncertain diagnosis. Therefore a statistical algorithm is favorable. The laser bio-photometry provides the experimental tables that are processed to compute the statistical parameters and to establish a statistic variable. The developed Evaluation function, E, allows the pathological processes finding, besides to the evaluation and monitoring of their evolution.

Measurements of the electrical characteristics in DC and AC regime for an epinephrine BOI device

The electrical properties of the chemical mediators at synapses level could be investigated in vitro, with some test biodevices. One of neurotransmitters, like epinephrine, placed on an insulator support and contacted with metal electrodes, provides a Biomaterials On Insulators - BOI-type, structure. The test device is inspired from the pseudo-MOS technique, frequently used in the Silicon On Insulator characterisation. The DC regime study allows some polarography experiments. A behavior like the Field Effect Transistor was also investigated in DC regime, biasing a third terminal - the gate. A gate voltage control on the current is expected. It is still linear, emphasising none inversion layer onset. The AC regime measurements of the BOI device provided some conductometry results, providing the epinphrine resistivity.

A two-terminals biodevice with a neurotransmitter solution

This paper proposes another destination for a biodevice. Frequently, the polarografy and amperometry methods are used to detect the analytes concentrations in biosensors. The purpose of the present device is to characterise the electrical properties of one of the most important neurohormone from the human body: epinephrine. Some experimental curves provide information about the non-linear electrical conduction through this neurotransmitter solution.

A silicon nanoporous membrane used for drug delivery

In the last years, biomedical applications of micro and nanotechnologies have been focused toward multifunctional devices. This paper describes the technological process controlled by the simulation of mechanical behaviour for microporous silicon membrane. These semipermeable structures belong to a complex biodevice used in vitro for cell-based assays and in vivo for immunoisolation and drug delivery application.