The skin is the largest organ in the body, and the fluid contained within it (interstitial fluid, ISF) has a volume greater than that of the vasculature. Despite this, ISF has been relatively little explored as a source of molecular information on both normal physiology and disease states. In part, this is because of the difficulty in accessing the fluid, typically employing microdialysis, reverse iontophoresis or hollow microneedles to extract the fluid. An alternative approach that promises both wide applicability and the capability for continuous measurement, employs <b>solid</b> microneedles to sense molecules within ISF in a minimally invasive fashion. This approach combines low-cost fabrication routes to a common base structure (the microneedle array) and versatile sensing chemistries for molecular recognition of the target analyte. The common base structure is an injection moulded patch, 15mmx15mm, with four separate microneedle arrays, each comprising sixteen microneedle projections in a 4x4 array. The microneedle array can be evaporatively metallised with a range of materials such as gold, platinum, silver or indium tin oxide. Figure 1 shows an electron micrograph of the typical microneedle structures. These microneedle structures can then be further modified with sensing layers including metal oxides, enzymes, polymers or nucleic acids, as well as outer layers to control mass transport and improve the interaction with tissues. Measurement methods are electrochemical and include amperometry and potentiometry.<br/>Evaluation of the microneedle arrays in volunteers has demonstrated that they are essentially painless and show no evidence of damage to the capillary bed. Sensor-based measurements for both metabolites, such as glucose, and drugs such as penicillin show the sensor responses track changes in ISF concentrations measured by microdialysis sampling and venous blood levels.

Minimally invasive microneedle sensor arrays: New window on the body

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.