Fig. 5: On demand, actuation-mediated rapid release (RR) of drug using STAR.

a RR enables convective flow of a model drug, methylene blue, from the therapy reservoir of STAR. Scale bar is 5 mm. b Photoacoustic images showing subcutaneously implanted STAR in a rat model: RR enables convective flow of drug analogue (red) from the therapy reservoir into the surrounding tissue pocket. c Schematic showing actuation-mediated RR overcoming fibrous encapsulation. d Snapshots from COMSOL Multiphysics simulation showing the rate-limiting diffusion barrier created by a FC and the ability to improve transport using RR. e Concentration of drug outside the FC comparing passive diffusion alone to RR at 200 s. f Concentration of drug outside the FC for a thin (100 μm) or thick (200 μm) FC with 1 or 5 RR actuation cycles. g In vivo images of rat model with two STAR devices implanted. Fluorescence shows the distribution of drug analogue Genhance 750. Red arrow indicates the device after undergoing RR actuation. h Temporal evolution of the drug diffusion area of Genhance 750 in passive (control) and RR actuated STAR, quantified by fluorescent IVIS imaging. i Blood glucose response to insulin in control (passive diffusion only) and in RR actuated (at t = 150 min) STAR devices, at 2 weeks following implantation. n = 4 animals per group; data represents means ± standard error of mean. p value calculated from paired one-tailed t-test.