"Smart" Needle Senses Tissue Pressure To Know Exactly Where It Is

An illustration of the i2T2 needle being used to deliver medication to the eye's suprachoroidal space



It's safe to say that no one likes the thought of getting a needle in the eye. If they have to, therefore, it would certainly be best if the procedure were performed correctly the first time. A new "smart" tissue-sensing needle is designed to help that happen.

Developed by scientists at Harvard-affiliated Brigham and Women's Hospital, the prototype device is known as the intelligent-injector for tissue-targeting, or the i2T2 for short.

Incorporating a standard hypodermic needle and parts from conventional syringes, it utilizes an integrated sensor to detect changes in applied pressure as its tip passes through different types of biological tissue, all of which have differing densities. After initially being "trained" on an organ such as the eye, it can subsequently determine exactly where its tip is within that organ – this is something that poses a challenge for humans, as they sometimes either under- or overshoot the target area.

The i2T2 could be particularly useful for delivering medication to the suprachoroidal space, located between the sclera and choroid layers in the back of the eye. In order to safely and effectively get pharmaceuticals to that space, the needle has to puncture the sub-millimeter-thick sclera but then immediately stop, so that it doesn't proceed into the retina (which is beneath the choroid).

Other non-eye targets could include the epidural space adjacent to the spinal cord, the subcutaneous tissue between skin and muscles, or the peritoneal space in the abdomen. In fact, in lab tests on animal tissue, the prototype successfully delivered a solution to the suprachoroidal, epidural and peritoneal spaces. In the case of the eye, the i2T2 was used to deliver stem cells, which are now often used in regenerative therapy.

"This intelligent injector is a simple solution that could be rapidly advanced to patients to help increase target tissue precision and decrease overshoot injuries," says Dr. Girish Chitnis, first author of the study. "We have completely transformed needles with a small modification that achieves better tissue targeting."

Pre-clinical trials are now being planned. A paper on the research, which took place in the lab of Dr. Jeff Karp, was recently published in the journal Nature Biomedical Engineering.

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