Electromagnetic Needleless Injector With Halbach Array Towards Intravitreal Delivery

The fear of needles and pain prevents some patients from seeking intravitreal treatment, which drives our group to develop a needleless device for performing intravitreal injections. A prototype for an electro-magnetically actuated needleless injector, based on Halbach arrays, is described and characterized in a laboratory setting. The implication of the prototype for needleless ocular drug delivery is investigated. This investigation is intended to improve drug delivery of glaucoma medication with a safe needleless approach. We detail the design aspects of the injector and characterized the device with custom-made phantoms. It was observed that, despite delivering the drug bolus to the center, the viscous vitreous phantom indicated vorticities similar to counter rotating vortex pairs, which could cause damage to the retina. The observed peak velocity during the phantom experiments was 6.1 mm/sec at the retinal layer, indicating that the delivery bolus can impart shear forces to the retina via the vitreous.