Fabrication of a fluid encapsulated dermal patch using multilayered SU-8

Abstract

A multilayer fabrication process using SU-8 has been demonstrated for the realization of a robust dermal patch, called the bio-fluidic integrable transdermal (B-FIT) microsystem. This device, which is worn in contact with the skin, samples and measures concentrations of bio-molecules such as glucose in interstitial fluid. The functional substructures of the device include fluidic reservoirs and capillaries, micro-heater element, and a colorimetric detection membrane. The heater elements are used to thermally ablate tiny pores through the surface layer of dead skin, allowing for easy diffusion of normally trapped bio-molecules to the skin surface. The capillaries and fluid containing reservoirs assist in the transport of bio-molecules from the skin surface to the detection patch situated on top of the device. The device offers the advantages of design flexibility, simplicity of fabrication, and the integration of metals with polymers. Highly aligned structures and good adhesion between metals and cured SU-8 layers have been achieved. A promising dry-release process using Teflon has been developed for the removal of the device from a supporting glass substrate used during fabrication. This paper presents the wafer-scale fabrication and characterization of prototype B-FIT devices.