Real-time visualization of fluid absorption by skin tissue following injection using optical coherence tomography

The skin is a potential site for delivering drugs such as vaccines and insulin, and novel devices such as microneedles can target the upper layers of the skin for effective drug delivery. Fluid flow into a deformable porous medium like skin tissue deforms the soft porous matrix, and consequently changes macroscopic parameters such as porosity and permeability. A major challenge in observing fluid flow into biological tissue is the highly optically scattering nature of tissue. Optical coherence tomography (OCT) is a promising biomedical imaging modality that provides cross-sectional images of the skin tissue in real-time with micron-scale resolution. We will present flow-induced tissue deformations captured by OCT during the injection of fluid at different viscosities and pressures into freshly excised porcine skin tissue through hollow microneedles. These tissue deformations are correlated with microfluidic sensor data of fluid flow-rate and pressure recorded during the injections. The experimental data can be used to extract displacement/strain fields in the tissue, and macroscopic skin properties such as permeability.