Capacitance‐to‐digital: A single chip detector for capillary electrophoresis

Abstract

A capacitance-to-digital converter integrated circuit was implemented in an automated CE device as a single chip detector. In this paper, design and hardware issues related to the fabrication and application of a miniature detector for contactless measurement of complex impedance are discussed. The capacitance-to-digital converter integrated circuit was used as the whole detector. The advantage of this setup is that the single integrated circuit provides digital data and neither additional signal conditioning nor analog-to-digital converter is required. Different separation conditions were used to evaluate the detection characteristics of the constructed detection unit. A 1 μM LOD for sodium and a 1.6 μM LOD for potassium ions were revealed for the detector. The detection system designed is competitive with miniaturized contactless conductivity detectors or UV absorbance detectors with respect to overall parameters (sensitivity, resolution, power consumption properties, and size). The obtained separation and detection results show that such detection technique can be used as an extremely low power consuming and space saving solution for CE detection with potential applications in environmental monitoring, process control, and various analytical measurements.

Cytotoxic attributes of antiviral plants rich in polyphenolic and volatile compounds

“…The CE system had a contactless conductivity detector integrated following the previously published procedures [18,19]. The gas chromatography-mass spectrometry system GC2010 and GCMS-QP2010 (Shimadzu, Japan) was used for the analysis of volatiles.…”

Contactless conductivity detection for analytical techniques— Developments from 2014 to 2016

“…Drevinskas and coworkers as well as Elkin designed detectors based on integrated circuits available from Analog Devices for the high resolution measurements of small capacitance changes (AD7745 and AD7746). These devices are intended for the measurement of signals from sensors, such as for pressure and humidity, and incorporate all the necessary circuitry, including an analog‐to‐digital convertor in a tiny surface mount package.…”

“…But as also Dasgupta has pointed out , this must be due to the fact that the integrated devices are meant to measure isolated capacitors, not circuitries consisting of several components, and thus produces a varying error signal when a changing resistive element is present (see the data sheet for the device). Nevertheless, the approach allows the construction of very compact detectors based on just a single integrated circuit, with good performance .…”

Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips

“…In contactless mode , the sample is isolated from the electrodes by a thin nonconducting material avoiding electrode fouling. There are several papers describing miniaturized C 4 D detectors .…”

“…In contactless mode , the sample is isolated from the electrodes by a thin nonconducting material avoiding electrode fouling. There are several papers describing miniaturized C 4 D detectors . The most widely used and commercially available capacitively coupled contactless conductivity detection (C 4 D) systems have a headstage format that can be matched with a fused silica capillary , but recently new C 4 D platforms have been introduced for microchips .…”