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Peter L Gehlbach, Gyeibgwoo W Cheon, Yong Huang, Jin Kang, ; Optical-Sensor Guided Intelligent Micro-injector for Retinal Therapy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1634.
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To demonstrate an intelligent micro-injector integrated with a common-path swept source optical coherence tomography (CP-SSOCT) fiber probe sensor that can accurately inject drug at a specific site or layer with an accuracy of less than 10 μm.
The novel intelligent microinjection system uses common-path swept source optical coherence tomography (CP-SSOCT) as a range sensor to detect the distance between the tissue and the tip of the CP-SSOCT fiber sensor attached to small gauge hypodermic needles (25-39 gauge). The kernel part of the micro-injector includes the aforementioned CP-SSOCT sensor, needle, a syringe, a conduit, lead zirconium titanate (PZT) motor with a rod to drive the syringe and a mechanical T-shape connector to integrate conduit, rod and needle. A 1310 nm swept source laser with a wide tuning range of 100 nm (Axsun Technologies, Inc.) was used as an OCT engine, operating at a 50 kHz repetition rate with an axial resolution of 19 μm. The injection depth is controlled and maintained by a real-time feedback PZT motor with a resolution of 5 μm, which also significantly reduces surgeon hand tremor and iatrogenic retinal contact using a closed-loop PID active control algorithm.
Using the microinjection system, we were able to rapidly and accurately inject solution into multiple sites in a retina phantom and also an ex vivo eye, accurately. At injection depths of 100 μm and 200 μm we achieved a best injection depth accuracy of on the order of 5 μm with +/- 5 μm error achieving less than 10 μm injection precision over a series of 100 micro-injections.
Here we present a novel CP-SSOCT- based intelligent micro-injector, and demonstrate precise, rapid, and uniform injection of drug with an accuracy of less than 10 μm. This novel approach may allow for precise drug delivery into previously inaccessible tissue structures such as the 250 μm thick retina.
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