Sonexos raises CHF 5M Pre-Series A to take plasma-based noise cancellation into industrial products

Sonexos SA (Lausanne) has raised CHF 5 million / €5.4 million in a Pre-Series A round led by Valquest Partners, with participation from Robert Bosch Venture Capital GmbH (Bosch Ventures) and a group of industry angels. The company — founded in 2022 by Mark Donaldson, a serial deep-tech entrepreneur who previously built SoundChip (acquired by DSP Group, now Synaptics) — holds an exclusive licence to Plasmacoustic Metalayer technology developed at EPFL (École Polytechnique Fédérale de Lausanne), and has since added four further patent families of its own, including two granted UK patents.

Fadi Noureddine, founder and Managing Partner of Valquest Partners, joins the Sonexos Board of Directors as part of the round.

The engineering problem Plasmacoustics targets

Conventional acoustic absorbers rely on porous materials that dissipate sound energy through viscous losses and thermal exchange. They work well at mid-to-high frequencies, broadly above 500 Hz. Below that threshold — the 30 Hz–500 Hz range where industrial fans, compressors, HVAC systems, and data-centre cooling infrastructure generate their dominant noise signatures — the physics require either very thick panels or very heavy mass-loaded barriers. Neither solution is compatible with modern product design targets for size, weight, and cost.

Sonexos' approach replaces the bulk with a software-controlled plasma layer at the product surface. The plasma interacts with incoming low-frequency pressure waves — across a stated range of 30 Hz to 1,500 Hz — and absorbs rather than reflects or transmits them, with no moving parts and no structural mass penalty. The technology is claimed to be tunable in real time through software, which would allow the absorption profile to adapt to changing operating conditions.

What the Pre-Series A funds

The CHF 5M now finances the gap between validated prototypes and customer-integrated hardware. Specific programmes include prototype-integration projects with lead OEM customers in HVAC, domestic appliances, data-centre cooling, automotive, and industrial noise control; engineering team growth in Switzerland and internationally; reliability and regulatory qualification; and an expanded IP protection programme.

"Engineers have always had to trade space and weight for silence," said Mark Donaldson. "Plasmacoustics removes that compromise. This financing carries it from working prototypes into our customers' products, at scale."

Bosch Ventures' participation carries specific weight. Robert Bosch's product portfolio spans the exact verticals — HVAC, automotive, industrial tools — where Sonexos aims to integrate. A corporate VC participation at this stage typically reflects an evaluation that the technology is worth tracking from the inside, not merely from a distance.

"Sonexos is addressing a fundamental engineering constraint with a technology that opens a much larger design space for low-frequency noise control," said Fadi Noureddine. "The combination of differentiated science, a strong intellectual-property position and progress with leading OEMs gives the company a credible path toward industrial production."