Sampling of Biological Interstitial Fluid by Porous Microneedle Array Patches

Interstitial fluid (ISF) that can be extracted from the skin contains various biomarkers related to health care as well as early diagnosis. Recently, porous Microneedle Array Patch (MAP) has been developed as a tool to analyze glucose concentration by extracting ISF from the body instead of traditional blood sampling [1]. In this study, we developed porous MAP to extract ISF for the analysis of various biomarkers included in ISF. In detail, the configuration of the porous MAP was revised in order to quickly separate the absorbing parts from the tape after ISF absorption. In our previously developed MAP configuration, the high adhesion between the surgical tape and the sensor sheet or microneedle made it impossible to separate them, including the ISF [2]. Thus, we developed a new configuration in which a removable tape and PET film are inserted between the surgical tape and the microneedles so that the sensing part including ISF can be separated as soon as the absorption of the ISF is completed. In addition, we changed the material of sensing part that mainly absorbs ISF, from the previous paper sheet to a non-woven fabric to improve the absorbency. With the new configuration, we performed puncture tests on agarose gels as well as even rats' skin, and confirmed the amount of ISF absorbed and the improved disassembly capability of the porous MAP. The puncture test on rats also confirmed that there was no damage to the skin. Finally, the stable sampling of the ISF amount for analysis is still a further issue, and we will make further improvements by introducing, for instance, an applicator to reduce the pressure difference when being applied to the skin during ISF absorption.