Design of capacitively coupled contactless conductivity detection sensor

As a newly developing measurement technique, capacitively coupled contactless conductivity detection ((CD)-D-4) is mainly studied and used in the research field of Analytical Chemistry for ion concentration/conductivity detection in a capillary. To expand the application fields of (CD)-D-4, in this work, a new (CD)-D-4 sensor which is suitable for conductivity detection in a millimeter scale pipe is developed. With the introductions of series resonance principle and a new shield configuration (the single-shield configuration), the negative influences of coupling capacitances and stray capacitances on the conductivity measurement are significantly reduced and the performance of the developed (CD)-D-4 sensor is improved. Experimental results show that the developed OD sensor is successful and its accuracy is satisfactory. Compared with the conventional (CD)-D-4 sensors, the developed (CD)-D-4 sensor can effectively implement conductivity measurement in larger scale pipes (up to 7.8 mm i.d.) and has the advantages of wider detection range and higher detection resolution. (c) 2012 Elsevier Ltd. All rights reserved.