Constitutive Law for Miniaturized Quantitative Microdialysis

Miniaturized microdialysis, a membrane-sampling technique, is in need for monitoring "tough" molecular substances such as neurotransmitters which exhibit limited diffusivity and fast clearance in synaptic space. This paper uses non-dimensional analysis and combinatorial simulations to predict the sampling performance of miniaturized microdialysis, prior to rigorously prototyping such small devices. As current microdialysis has sampling resolution too rough to meet the needs, one aim of this paper is to understand how best miniaturized microdialysis would improve the sampling performance, and to what degree. Our results of numerical simulations and curve-fitting extrapolation suggest improved temporal resolution (at least ten times better) is achievable, while retaining the relative recovery, a key factor for quantitative microdialysis, at an acceptable level. To the limit of theoretical downscaling in microdialysis, the results also suggest the need for new operation principles for miniaturized microdialysis.