Several investigators have shown that transdermal assay of interstitial fluid can be used for diagnosis. This fluid is an attractive target because it contains many of the same constituents as blood plasma and suction blister fluid at clinically relevant concentrations. The sampling of interstitial fluid for real-time assay requires techniques that are sensitive, rapid, painless, minimally invasive and easy to use by patients. Microneedles can be incorporated into biosensors with subsequent use of these platforms for continuous monitoring or bio-chemical detection of analytes in the dermal interstitial fluid. Microneedles can detect biomarkers in/from the skin in a minimally invasive fashion thus facilitating (near-) real-time diagnosis. In this chapter, the use of microneedles for diagnostic testing is examined.
