Microplasma Generator


Tufts University researcher, Jeff Hopwood, has developed a low-cost and high-efficiency source that allows plasma surface treatment at atmospheric pressure.


Non-thermal atmospheric plasmas have been demonstrated to be safe for human life and efficacious for anti-itch, anti-fungal, anti-bacterial and anticancer treatment. Ionized particles such as electrons, ions, reactive oxygen species (ROS, e.g. ozone), reactive nitrogen species (RNS), and UV radiation in the plasma are believed to have a deleterious impact on bacterial membranes. A variety of microplasma sources have been developed but the need remains for a low-power source that delivers a high flux of ionized particles without damaging the underlying tissue.


Non-thermal atmospheric pressure plasma for use in plasma medicine.  A microwave induced plasma (MIP) source based on a microstrip split-ring resonator (MSRR) that operates at atmospheric pressure. Given the geometry of the microstrip, the maximum rf voltage difference occurs across the gap, favoring the discharge breakdown in this region while minimizing losses in the rest of the device. Since the gap is created between the ends of the same microstrip, no dc potential exists across the gap i.e. no dc bias is applied to the plasma. This unique feature minimizes the energy lost in accelerating ions in the plasma sheaths, resulting in a threefold increase in ion flux over the commonly studied technology (viz. dielectric breakdown device). In addition, the low voltage use precludes damage to the underlying tissue.


Competitive Advantage

This microplasma source requires less than 3 W at ~900 MHz to self-start argon and air discharges. The discharge generated with a microstrip source is not in thermal equilibrium, allowing efficient air-cooled operation. Efficiencies of up to 70% both at low pressure and atmospheric pressure are achieved with simple and inexpensive designs while achieving high fluxes of low-energy ionized particles that can enable superior bactericidal and anti-cancer properties. Simple and portable.  20-30 V operation.  Manufacturable by microfabrication.  Miniaturizable low-cost and high reliability.  Continuous plasma with 3x higher ion flux than the current technology (DBD); potentially enhanced disinfection efficacy.




Biological surface disinfection

Wound healing

Anti-cancer treatment


Intellectual Property

US Patent No. 9,460,884 (Issued on October 4, 2016)


Tufts University Invention T001762 




Licensing Contact

Suresh Annavarapu