Smart Photons from Microplasmas: Emerging Applications in Communications, Microelectronics and Healthcare

Low-temperature microplasmas are efficient sources of ions, electrons, reactive species, and photons. Among their various applications, microcavity plasma arrays are particularly valuable for unique photon generating or interaction that enable emerging photonic technologies. This paper presents recent advancements in microplasma photonics across four key areas: The first area is precision timekeeping. Microplasma-based mercury ion lamps (²⁰²Hg⁺, 194.23 nm) have been integrated into compact clock systems (under 1000 cc), achieving exceptional frequency stability at the 10⁻¹⁴ level, more than two orders of magnitude better than that of conventional miniature clock technologies.

Microplasmas enable the creation of tunable 3D photonic crystal structures operating in the 120–170 GHz range. When low-temperature plasma (in atmospheric pressure Argon) fills the dielectric channels, the resonance frequency shifts by up to 1.6 GHz. Inserting microplasmas into layered materials block significantly enhances signal attenuation, exceeding 30 dB.

For microelectronics applications, microplasma sources emitting vacuum UV photons (~7.2 eV) are capable of dissociating covalent bonds in organic compounds, enabling precise surface nanopatterning and material modification. These sources also facilitate room-temperature deposition of uniform dielectric layers such as SiO₂ and Al₂O₃ from liquid-phase precursors. Their uniform, large-area output supports high-resolution processing without energy-intensive fabrication steps. Additionally, pulsed deep-UV microplasmas can rapidly switch high-voltage, wide-bandgap semiconductor devices-such as diamond-based PCSS-within sub-microsecond timeframe, unlocking new potentai in advanced power electronics.

Lastly, microplasma lamps emitting 222 nm far-UVC radiation from KrCl* excimers have shown high efficacy in inactivating airborne pathogens, including SARS-CoV-2, flu, and RSV, while remaining safe for human and animal exposure. These flat plasma photonics are increasingly deployed in occupied public spaces to help prevent biological threats and enhance food safety.