Next time you visit the doctor, your physician might not be kidding when he snaps his glove and proclaims, “This won’t hurt a bit.”

Researchers from the UCSB Chemical Engineering Dept. – in collaboration with research teams from UC Berkeley and pharmaceutical company StrataGent Life Sciences, Inc. – have developed a “liquid jet injector,” which could potentially be used to painlessly deliver treatments that are typically administered through needles, like disease vaccinations and insulin.

Though this is not the first needle-less injection device, researchers say this particular version, called the MicroJet, hurts less than previous ones and reduces needle-stick injuries like bruising.

“The MicroJet device delivers drug jets into superficial layers of skin,” UCSB Associate Professor of Chemical Engineering Samir Mitragotri said. “This avoids direct contact of jets with blood vessels and nerves, which are located in deeper skin layers. This helps reduce pain and bleeding, which is commonly observed in conventional jet injections.”

Mitragotri said he – along with bioengineering graduate student Anubhav Arora and recent UCSB graduate Joy Baxter – initiated developments for the MicroJet device three years ago after spending considerable time studying conventional needle-less injectors.

The almost painless alternative pulses small amounts of liquid – 2 to 15 nanoliters – into the body at approximately 100 meters per second. The administered treatment continues to diffuse through to the blood stream and into the rest of the body. Arora said the depth of penetration of the jets is only 200 to 400 microns, or one-millionth of a meter. Earlier injections went as deep as 2 mm.

Sergio Landau, who has worked in the field of needle-less injections for 30 years and is currently an employee with Bioject, said needle-less injections require a large amount of force to penetrate the skin, and thus a more expensive apparatus than current treatment administration forms that use needles.

“The need for high force makes the product expensive,” Landau said.

Arora said the price of the new product has yet to be decided based on many cost-determining factors for customers, such as manufacturing and product development.

Mitragotri said this type of device could be especially useful in diabetes treatments because the patient could wear an insulin injector on his or her arm, allowing treatment to be delivered painlessly throughout the day.

This form of treatment is likely to be developed with the new MicroJet, Arora said.

“The design also offers continuous mode of operation as against single shots with the earlier design,” Arora said. “This means it can be developed into a continuous operating device.”

Despite its many benefits, Mitragotri said the MicroJet makes diffusion of drugs a somewhat longer process.

“The drugs have to diffuse from the site of delivery to the bloodstream, so it will take a little longer for the drug to take effect,” Mitragotri said. “However, the delay was relatively small in our studies.”

With traditional injections that involve a needle, Arora said the patient will experience effects 30 minutes after a treatment is injected, whereas it could take up to an hour before the effects of needle-free treatment administration could be seen.

While researchers did not observe side effects during early experimentation, Mitragotri said they would begin conducting research on humans within the next few years.

“Getting the device approved by the FDA requires substantial efforts,” Mitragotri said. “Things look good so far, but more work needs to be done before that can happen.”