MASS-TRANSFER PROPERTIES OF MICRODIALYSIS PROBE FOR MONITORING GLUCOSE LEVEL IN SUBCUTANEOUS TISSUES

The purpose of this paper is to develop a microdialysis probe with hig her recovery for continuous sensing of glucose concentration in subcut aneous tissue. The value for the mass transfer coefficient obtained by in vivo experiment is compared with that by in vitro experiment. Opti mum conditions for fast response and high recovery are determined as a perfusion rate of 120 mu l . h(-1) and a probe length of 15 mm using regenareted cellulose capillary membrane. The relationship between the glucose concentration in blood and the glucose concentration in subcu taneous tissues was examined by inserting probes underneath the skin, and perfusing a dialysate of different glucose concentrations. The glu cose concentration in subcutaneous tissues is found to be almostly con sistent with that in blood. The mass transfer coefficient external to the probe in subcutaneous tissues, k(ext) = 1,2 similar to 2.4 mu m . s(-1), is 20 similar to 50% of the values of those obtained by in vitr o experiments (k(ext) = 5.7 similar to 6.7 mu m . s(-1)).