A novel diffusion cell ideal for the study of membrane extraction/permeation processes and for device/sensor development

[[abstract]]A novel diffusion cell has been constructed which allows study of membrane extraction/permeation processes in a more realistic approach. To examine the performance of this new design, the extraction of glucose in this diffusion cell by reverse iontophoresis has been studied. Reverse iontophoresis refers to the passage of a low level of current through a synthetic or biological membrane to promote the transport of both charged and neutral molecules. The performance of this diffusion cell is compared with results from the extraction studies using a diffusion cell developed by Connolly et al. [P. Connolly, C. Cotton, F. Morin, Opportunities at the skin interface for continuous patient monitoring: a reverse iontophoresis model tested on lactate and glucose, IEEE Trans. Nanobiosci. 1 (1) (2002) 37-41] and results from the human glucose extraction studies in vivo. This newly developed diffusion cell can be easily fabricated for membrane extraction/permeation studies and for device and sensor development

Reverse iontophoresis: A non-invasive technique for measuring blood lactate level

[[abstract]]Blood lactate monitoring is beneficial to many patients, e.g. critical care patients. However, there are very few non-invasive or continuous monitoring systems for this parameter and significant clinical benefit could be achieved if such systems were readily available. Therefore, the aim of the current study was to investigate the possibility of non-invasively extracting lactate from blood through skin using reverse iontophoresis to monitor blood lactate levels in humans. In vitro reverse iontophoresis studies have indicated that the optimum switching mode for reverse iontophoresis of lactate is continuous direct current but application of current combined with electrode polarity reversal every 15 min was suggested to be used in humans. The reverse iontophoresis technique was applied to 10 healthy volunteers and lactate was successfully extracted through their skin into the methylcellulose gel of the electrodes. A moderate correlation (r2 = 0.6) between lactate concentrations in collection gels and lactate levels in the blood was observed after an outlier was removed from the regression equation. The result suggests that it may be possible to non-invasively monitor the blood lactate levels using reverse iontophoresis technique

The effect of pulsed bipolar dc on the simultaneous extraction of glucose and lactate by reverse iontophoresis

[[abstract]]This in vitro study focused on the investigation of the effect of current waveform on simultaneous glucose and lactate extraction by reverse iontophoresis. Experiments were performed using diffusion cells. An iontophoretic current (0.3 mA cm-2) at four different current waveforms (a combination of 0-, 5-, 10- and 15-s pulse intervals and 15-min polarity reversal intervals) were applied for 90 min via Ag/AgCl electrodes. Glucose and lactate extraction were quantified by spectrometric analysis. The result suggests that extraction of glucose and lactate by pulsed bipolar current are pulse-frequent dependent and pulsed bipolar current at a particular pulse-frequent is found to be more effective on glucose and lactate extraction than bipolar current. © 2007 Elsevier B.V. All rights reserved

A novel diffusion cell ideal for the study of membrane extraction/permeation processes and for device/sensor development

A novel diffusion cell has been constructed which allows study of membrane extraction/permeation processes in a more realistic approach. To examine the performance of this new design, the extraction of glucose in this diffusion cell by reverse iontophoresis has been studied. Reverse iontophoresis refers to the passage of a low level of current through a synthetic or biological membrane to promote the transport of both charged and neutral molecules. The performance of this diffusion cell is compared with results from the extraction studies using a diffusion cell developed by Connolly et al. [P. Connolly, C. Cotton, F. Morin, Opportunities at the skin interface for continuous patient monitoring: a reverse iontophoresis model tested on lactate and glucose, IEEE Trans. Nanobiosci. 1 (1) (2002) 37-41] and results from the human glucose extraction studies in vivo. This newly developed diffusion cell can be easily fabricated for membrane extraction/permeation studies and for device and sensor development

Reverse iontophoresis: a non-invasive technique for measuring blood lactate level

Blood lactate monitoring is beneficial to many patients, e.g. critical care patients. However, there are very few non-invasive or continuous monitoring systems for this parameter and significant clinical benefit could be achieved if such systems were readily available. Therefore, the aim of the current study was to investigate the possibility of non-invasively extracting lactate from blood through skin using reverse iontophoresis to monitor blood lactate levels in humans. In vitro reverse iontophoresis studies have indicated that the optimum switching mode for reverse iontophoresis of lactate is continuous direct current but application of current combined with electrode polarity reversal every 15 min was suggested to be used in humans. The reverse iontophoresis technique was applied to 10 healthy volunteers and lactate was successfully extracted through their skin into the methylcellulose gel of the electrodes. A moderate correlation (r2 = 0.6) between lactate concentrations in collection gels and lactate levels in the blood was observed after an outlier was removed from the regression equation. The result suggests that it may be possible to non-invasively monitor the blood lactate levels using reverse iontophoresis technique

The effect of pulsed bipolar dc on the simultaneous extraction of glucose and lactate by reverse iontophoresis

This in vitro study focused on the investigation of the effect of current waveform on simultaneous glucose and lactate extraction by reverse iontophoresis. Experiments were performed using diffusion cells. An iontophoretic current (0.3 mA cm−2) at four different current waveforms (a combination of 0-, 5-, 10- and 15-s pulse intervals and 15-min polarity reversal intervals) were applied for 90 min via Ag/AgCl electrodes. Glucose and lactate extraction were quantified by spectrometric analysis. The result suggests that extraction of glucose and lactate by pulsed bipolar current are pulse-frequent dependent and pulsed bipolar current at a particular pulse-frequent is found to be more effective on glucose and lactate extraction than bipolar current