A passive MEMS drug delivery pump for treatment of ocular diseases

Abstract

An implantable manually-actuated drug delivery device, consisting of a refillable drug reservoir, flexible cannula, check valve, and suture tabs, was investigated as a new approach for delivering pharmaceuticals to treat chronic ocular diseases. Devices are fabricated by molding and bonding three structured layers of polydimethylsilox-ane. A 30 gauge non-coring needle was used to refill the reservoir; this size maximized the number of repeated refills while minimizing damage to the reservoir. The check valve cracking pressure was 76±8.5 mmHg (mean ± SE, =4);the valve sustained > 2000 mmHg of reverse pressure without leakage. Constant delivery at 1.57±0.2µL/sec and 0.61±0.2µL/sec (mean ± SE, =4) under 500 mmHg and 250 mmHg of applied pressure, respectively, was obtained in benchtop experiments. The valve closing time constant was 10.2 s for 500 mmHg and 14.2 s for 250 mmHg. Assembled devices were successfully demonstrated in benchtop,ex vivo , and in vivo experiments.