Many challenges are encountered in the practical application stage of the impedimetric biosensing technique although an ever-increasing interest has been drawn to this area. Lack of a fast and simple readout method and the corresponding portable, low-cost instrument is one of the greatest obstacles. Here we described a potential attractive solution to this problem, specifically impedance spectra are measured by perturbing the system under investigation with a small-amplitude potential step followed by appropriate processing of the resulting chronoamperometric current response. This measurement strategy makes fabricating a portable impedance measurement instrument for routine analysis with low-cost possible. We constructed such a device which was credit-card sized and mainly comprise a mixed signal microcontroller and several operational amplifiers. The reliabilities of the technique/device were verified by experiments carried out with real electrochemical samples. Relevant problems and limitations of this technique are discussed as well. Obvious advantages with respect to the simplicity, rapidity and ease of miniaturization make the technique/device a competitive candidate for practical point-of-care applications. (C) 2011 Elsevier B.V. All rights reserved.