Carbon microneedles: Low-cost, painless injections

Even after 15 insertions, the patch and needles remained intact

January 05, 2019 06:32 pm | Updated 06:33 pm IST

The new carbon microneedles are 400 micrometres long and can pierce painlessly, says Richa Mishra (standing).

The new carbon microneedles are 400 micrometres long and can pierce painlessly, says Richa Mishra (standing).

Tiny needles less than 1 mm in size have been developed by researchers from Indian Institute of Technology (IIT) Kharagpur. When arranged on a patch, the tiny hollow microneedles can be used for painless drug delivery.

Last year, the team had developed microneedles from a widely used photosensitive polymer (SU-8). Since the needles were not hard enough and biocompatible, they modified it using a simple process of extreme heating or pyrolysis. This produced glassy carbon needles which were almost 300 times stronger than the original ones. Since it was made of carbon it was also biocompatible.

Heating removed most of the nitrogen and oxygen in the polymer and the needle were solely made of carbon. The needles showed no toxicity when tested on mice models, says Prof. Bidhan Pramanick who completed his post-doctoral research from the institute. He is one of the corresponding authors of the work published in Nature Microsystems & Nanoengineering.

The needles were arranged in a patch (10 X10) and tested for drug delivery. The patch was attached to a 5 ml syringe and flow rate studied. They found the flow corresponds to the inlet pressure suggesting that drug delivery can be controlled by managing the pressure.

Drug delivery

“We are now working on developing a drug reservoir and micropump which can be attached to the patch for controlled drug delivery. Just like a band-aid, we can fabricate a dia-aid that can be used by diabetic patients for painless insulin administration,” says Tarun Kanti Bhattacharyya from the Department of Electronics and Electrical Communication Engineering at the Institute and one of the corresponding authors of the work. “Though we cannot bring down the cost of insulin, this patch can reduce the device cost by almost 50%.”

When a needle is inserted into the skin, it experiences resistance from the skin. A good needle should be able to overcome the forces to penetrate the skin. Using compression and bending tests, the researchers found that the needles did not break or bend when force was applied. The patch was tested on mouse models and even after 15 insertions, the patch and needles remained intact. “We found that the new carbon microneedles overcame the resistive forces of our skin and was able to successfully pierce the skin. And as the needles are only 400 micrometer long, it will be completely painless,” says Richa Mishra, PhD scholar at the institute and first author of the work.

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