Researchers Pioneer Painless Microsyringe for Drug Delivery

Imagine receiving an injection, but feeling little or no pain.

Imagine babies being vaccinated without crying.

UC Berkeley engineers are helping to make that dream a reality.

Postdoctoral mechanical engineering researcher Boris Stoeber and mechanical engineering professor Dorian Liepmann have designed a convenient, relatively pain-free syringe.

The device, dubbed a chiclet because of its small square shape, delivers its contents into the body through a cluster of microneedles on the bottom surface when pressure is applied on top.

These needles, which measure about one-fifth the width of a human hair, are so short that they do not penetrate deeply enough to stimulate pain receptors underneath the skin.

"You don't see the needle and you don't feel it," Stoeber said.

The syringe works because the needles are long enough to penetrate the tough outermost coating of the epidermis.

Underneath this layer, bodily fluids can absorb the syringe's contents and bring them into the bloodstream.

Chiclet syringes are more versatile than traditional needle syringes-they can be applied almost anywhere on the hands and arms, except where the tough outer layer of skin is too thick, such as on calluses of the palms.

The syringes also have the advantage of being relatively easy to prepare.

Like fruit punch and hot chocolate, some drugs are available in powder form.

To make the drugs usable in a traditional syringe, one needs to add water, a requirement which could be a problem.

"In third-world countries, you many not have clean water to prepare them," Stoeber said.

Stoeber's creation is a possible way around that obstacle.

Stoeber envisions pre-filling the chiclet syringes with a concentrated suspension, and allowing the body to just add water.

The syringe, which is made of silicon, is a simple example of a micro-electromechanical system (MEMs).

"This is all just one rigid structure," Stoeber said. "In general, MEMs can have moving parts and many combined electronics."

Because MEMs are made in a way similar to microchips, existent manufacturing technology could be applied to mass production of the syringes, streamlining the process in the future.

The sheer simplicity of the device could explain its primary limitation.

"The amount you inject may not always be exactly the same, but if you use antibiotics and vaccines, then you probably could overdose a little bit; it wouldn't be very dangerous," said Stoeber.

Raja Sivamani, a graduate student in the Joint UCSF/UCB Bioengineering program, is beginning clinical tests on the syringe.

"Basically I am looking to see if the microneedles, that were designed by Boris can successfully and painlessly pass drugs through the skin," Sivamani said. "Preliminary tests show that the microneedles are able to pass the drugs through more effectively when compared to simply applying the drug to the skin surface."

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