P. Phasukkit

Finite-Element Analysis and In Vitro Experiments of Placement Configurations Using Triple Antennas in Microwave Hepatic Ablation

This study presents analyses of triple-antenna configurations and designs for microwave (MW) hepatic ablation using 3-D finite-element (FE) analyses verified by in vitro experiments. Treatment of hepatic cancer often requires removal or destruction of large volume lesions. Using multiple antennas offers a potential solution for creating ablation zones with larger dimensions, as well as varied geometrical shapes. We performed both 3-D FE analyses and in vitro experiments using three identical open-tip MW antennas simultaneously, placing them in three types of configurations-ldquolinear array,rdquo ldquotriangular,rdquo and ldquoT-shapedrdquo arrangements. We compared coagulation volumes created, as well as temperature distribution characteristics, from the three-antenna arrangements after power delivery of 50 W for 60 s. We also performed additional tests using nonidentical antennas (open tip, slot, and slot with insulating jacket) for the three configurations. The results illustrate that arranging antennas in the ldquoT-shapedrdquo pattern destroyed more unwanted tissues than those found when using ldquolinear arrayrdquo and ldquotriangularrdquo arrangements, with maximum coagulation width and depth of 46 and 81 mm, respectively, and coagulation volume of 30.7 cm3 . In addition, using nonidentical triple antennas caused variations in coagulation zone characteristics, and thus, the technique could be applied to treatment situations where nonsymmetric coagulation zones are required.

High-sensitivity humidity sensor utilizing PEDOT/PSS printed quartz crystal microbalance

In this work, quartz crystal microbalance humidity sensor was fabricated by inkjet printing technique. Poly (3, 4-ethylenedioxythiophene)/poly-styrene-sulfonic acid (PEDOT/PSS), one of the most widely used polymer composites, was printed on QCM electrode as sensing layer using Dimatrix material inkjet printer. The main advantage of this coating method is its high precision of solution coating with accurately controlled volume and area. The printed layer was varied from 1 to 20 layers. With 20 PEDOT/PSS printed layers, the humidity sensitivity is found increased by more than three orders of magnitude compared to uncoated QCM. In addition, the PEDOT/PSS coated QCM exhibits fast humidity detection with short response and recovery times. Thus, the PEDOT/PSS printed on the QCM electrode is an effective way to improve humidity-sensing characteristic of QCM.

A new mixed-mode quadrature oscillator using a single CCCDTA

This paper presents a new current-controlled mixed-mode quadrature oscillator using only a current controlled current differencing transconductance amplifier (CCCDTA), two grounded capacitors and one MOS resistor. The structure is beneficial to monolithic integrated circuit implementation. The proposed circuit provides two quadrature voltage outputs and two quadrature current outputs. The quadrature current outputs also offer the feature of high output impedance. The oscillation condition and the oscillation frequency of the oscillator are independently controllable. PSPICE simulation results which confirm the theoretical predictions are also given.

Opened-tip applicator and ex vivo experimental results for microwave breast cancer ablation

Breast cancer is one of the main health hazard that threatening women life all over the world. Not only her own daily life, but also her own family whom suffering from this poor fate. Besides from a breast resection, microwave ablation is also another effective therapeutic technique for glandular tissue cancer treatment due to its minimal invasive maneuver. In this paper, we propose a study of an opened-tip applicator ablation for breast cancer therapy. The investigation was preliminary performed by using finite element method to analyze a characteristic of antenna and to simulate a 2.45 GHz electromagnetic wave phenomenon in living tissue then following by ex vivo experiment with female swine breast. In term of FEM simulation, full 3D distribution pattern of SAR, temperature and also estimated destructive tissue area in a complicated CAD model of cancerous breast was analyzed. Real ablation with an ultrasound-guided applicator insertion was implemented to confirm an effective result. This study not only shows a promising result but also encourage us to develop an advance microwave ablation system in near future.

Effect of phase difference in multi-antenna microwave thermal ablation for breast cancer treatment

It was realized that cancer in breast is one of the most health hazards threatening women around the world for many years. Thermal ablation by using microwave energy is another alternative surgical maneuver due to its minimally invasive therapeutic technique. In this research, we investigate an effect of phase difference between three adjacent openedslot coaxial probes in a multiple antenna alignment of microwave thermal ablation system for breast cancer treatment. FEM by using COMSOL is an implementation tools to simulate for 0, 45, 90, 135 and 180 degree of phase difference. 3D Simulation results show that temperature distribution pattern, destructive volume and SAR in breast tissue are affected from those phase-shift utilization in multi-antenna system significantly.

Finite element analysis on phase shift effect of multi-antenna array alignment for microwave liver ablation

Microwave ablation for liver cancer treatment has been widely performed due to its minimal invasive technique both single and multi probe. Even though, multi antenna ablation system provide a larger destroy area, however effect of phase shift difference between each antenna is still challenge to be investigate for total ablation result. In this research, we propose a preliminary investigate of phase shift effect to a multi antenna system. Two probes array and three probes array was configured as a multi antenna liver ablation system based on each coaxial opened-slot antenna. By using FEM analyze, we present a full 3D simulation results of those multiple antenna system as phase shift between each probe was varied. Total destroy volume is effected significantly when phase shift was differed from 90°, 180° and 270°.

A Study of an Intubated Tracheal Air Flow in a Cuff-Leak Testing Procedure

During an artificial ventilation, an endotracheal tube (ETT) must be inserted into patient airway and following by a balloon cuff blowing in order to function as an artificial airway. However, this implementation adversely affects to a tracheal tissue and all sensitive area and probably damaging a larynx and vocal cord zone. After ETT was removed, some patients always suffering with a larynx or tracheal edema symptom in which patient airway is narrowed due to a long term pressurization by the ETT balloon cuff and causing a difficulty in his spontaneous breathing. In general, a cuff leak test is performed in order to predict a larynx or tracheal edema possibility before ETT extubation from an air volume difference between an inspiration and expiration. In this paper, an investigation of an airflow pattern and air velocity which able to imply as an air volume in the cuff leak test process is proposed in order to understand and support a prediction of the tracheal edema. The study was performed with no edema and edema case at 10, 30 and 50% of trachea internal diameter. The simulations indicate that airflow pattern shows some affects when edema region is higher than 10%. Even though, this preliminary study was intently implemented in a simple intubated trachea model, however the obtain results guide us a practical information and will be used as a basic implementation for a further study, especially in case of variety in the ETT cuff shape and pressure or in cuff less ventilation even more complication case in the near future.

Computational analysis of blood parameters separate by centrifuge technique

This article is purpose of the computational fluid dynamic (CFD) simulation for blood parameters separated by centrifuge machine which has different spinning velocities. The structure of the machine, as a fixed tube at 30 degrees from the base is used to prove that the precipitate of the bloods 2 parameters, such as blood cell and plasma, by using the simulation from computer In three dimensional (3D) symmetry modeling to study the change of the precipitate in centrifuge at different velocity of spinning. At 2000 rpm, 3000 rpm, 4000 rpm and 5000 rpm(round per minute) the result of this simulation showed the density of blood as low density in the top of the blood its mean plasma and high density at the bottom of the tube its mean blood cell. From the model in centrifuge can prove that in each different level of the density from velocity of spinning that useful for study to improvement of blood parameters separated by used computer simulation.

Versatile Voltage-Mode Multifunction Biquadratic Filter Employing Only Eight Single-Ended OTAs and Two Grounded Capacitors

This paper presents a new versatile multifunction voltage-mode biquadratic filter with three inputs and four outputs employing single-ended operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed circuit provides the following advantages: (i) employment single-ended OTA and grounded capacitor which is highly suitable for integrated circuit implementation, (ii) simultaneously realize voltage-mode low-pass, band-pass, highpass, band-stop and all-pass filter responses by appropriately connecting the input and output terminals, (iii) no need to employ inverting-type input signals and component-matching condition for realizing these filter responses, (iv) orthogonal set the natural frequency and the quality factor, (v) electronic control the natural frequency, (vi) low active and passive sensitivities. The workability of the proposed filter is confirmed by PSPICE simulator. From simulation results, it can be expressed that the proposed circuit agrees well with theory.

Improving WLAN location determination system by analyzing human factor effect

This paper presents an improvement of deterministic WLAN location determination system using finite element method for calculated HEF constant, ones to add the last value before decision of conventional method. From the results, when using HEF, constant improved the value before decision position for LLR and RADAR yielded to be obvious. It had minimum error distance below 2 meters.