Piezoelectric-driven plasma pen with multiple nozzles used as a medical device: risk estimation and antimicrobial efficacy

A commercial air-fed and piezoelectric-driven plasma pen (piezobrush(R), relyon plasma GmbH, Regensburg, Germany) including three different nozzles was investigated for its suitability as a medical plasma device. In this regard, potential risk factors for human health, which originate from gas temperature, thermal output, patient leakage current, ultraviolet radiation and gas emissions, were assessed according to DIN SPEC 91315:2016-06. As a result, safe treatment distances were determined for each nozzle. The antimicrobial efficacy was investigated subsequently by inhibition zone assays with five different clinical relevant microorganisms. All results were compared to an approved medical plasma source fed with argon (kINPen(R) MED, neoplas tools GmbH, Greifswald, Germany). It was observed that the antimicrobial efficacy differs not only between the two devices as a result from different feed gases, but also between the nozzles. This could be traced back to a different plasma chemistry, which accompanying Fourier-transform infrared absorption spectroscopy suggests. The measured physical properties of the piezoelectric plasma pen at the determined operating parameters do not show human health risks. Due to its distinct antimicrobial efficacy, the piezoelectric plasma pen shows a high potential for a medical application.