Simple Circuit Equivalents for the Constant Phase Element

The constant phase element (CPE) with a frequency-independent negative phase between current and voltage is used extensively in e.g. the bioimpedance and electrochemistry fields. Its physical meaning is only partially understood. Here we show that the responses of both the common capacitive CPE as well as the inductive CPE are exactly the same as those of simple RL and RC circuits where the inductor's or capacitor's value increases linearly with time. The resulting step and impulse responses are found and verified by simulation with the Micro-Cap simulation program. The realization with time-varying components correlates with known time-varying properties in applications.Comment: 14 pages, 4 figure

Bioimpedance-based authentication of defrosted versus fresh pork at the end of refrigerated shelf life

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Diabetic foot assessment using skin impedance in a custom made sensor-sock

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Assessment of Intestinal Ischemia–Reperfusion Injury Using Diffuse Reflectance VIS-NIR Spectroscopy and Histology

A porcine model was used to investigate the feasibility of using VIS-NIR spectroscopy to differentiate between degrees of ischemia–reperfusion injury in the small intestine. Ten pigs were used in this study and four segments were created in the small intestine of each pig: (1) control, (2) full arterial and venous mesenteric occlusion for 8 h, (3) arterial and venous mesenteric occlusion for 2 h followed by reperfusion for 6 h, and (4) arterial and venous mesenteric occlusion for 4 h followed by reperfusion for 4 h. Two models were built using partial least square discriminant analysis. The first model was able to differentiate between the control, ischemic, and reperfused intestinal segments with an average accuracy of 99.2% with 10-fold cross-validation, and the second model was able to discriminate between the viable versus non-viable intestinal segments with an average accuracy of 96.0% using 10-fold cross-validation. Moreover, histopathology was used to investigate the borderline between viable and non-viable intestinal segments. The VIS-NIR spectroscopy method together with a PLS-DA model showed promising results and appears to be well-suited as a potentially real-time intraoperative method for assessing intestinal ischemia–reperfusion injury, due to its easy-to-use and non-invasive nature.publishedVersio

Interpretation of the pinched point position in human skin memristor measurements

It is shown that human skin acts like a memristor but systematic studies on skin memristance are not published, yet. If e.g., a low frequency voltage is applied to human skin and the current is measured, a hysteresis loop can be seen in the voltage-current plot. In skin measurements, the pinched point of the hysteresis loop can be shifted from the coordinate origin. In this paper, possible reasons for this observation shall be investigated and interpreted by the use of simulation. Two example measurements on human skin are presented, as well