Contactless Impedance Sensors and Their Application to Flow Measurements

نویسندگان

  • Frantisek Opekar
  • Petr Tuma
  • Karel Stulík
چکیده

The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Contactless EMG sensors embroidered onto textile

To obtain maximum unobtrusiveness with sensors for monitoring health parameters on the human body, two technical solutions are combined. First we propose contactless sensors for capacitive electromyography measurements. Secondly, the sensors are integrated into textile, so complete fusion with a wearable garment is enabled. We are presenting the first successful measurements with such sensors. ...

متن کامل

Effects of Stray Capacitance to Ground in Bipolar Water Impedance Measurements Based on Capacitive Electrodes

 Liquid impedance measurements based on capacitive (or contactless) electrodes overcome electrode polarization problems but are affected by stray capacitance from the material being measured to ground, the same as measurements with direct-contact electrodes. This study shows that the effects of that capacitance depend on the impedance being measured and for bipolar impedance measurements they ...

متن کامل

Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures

UNLABELLED The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ult...

متن کامل

Nanowires network for biomolecular detection using contactless impedance tomoscopy technique.

Here we present the detection of ultralow concentrations of biomolecules in a device made from a polycarbonate membrane containing a network of gold nanowires and using a "contactless" impedance tomoscopy technique. The sensor comprises a thin dielectric layer with two parallel band electrodes on the one side and a microchannel containing gold nanowires onto which the adsorption of antibodies o...

متن کامل

Contactless Conductivity Detection in Ceramic Technology for On-Chip Electrophoresis

A capacitively coupled contactless conductivity detector produced in Low Temperature Co-fired Ceramic (LTCC) technology for microchip capillary electrophoresis (CE) is reported in this work. Electrodes located outside the measurement channel are used to sense impedance variations caused by conductive ions. The application of LTCC in combination with contactless conductivity detection is very pr...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره 13  شماره 

صفحات  -

تاریخ انتشار 2013