Sonexos, CHF 5M pre-Series A for plasma noise control
Sonexos says it can absorb low-frequency noise with a thin plasma layer and no moving parts. On 21 October 2026 the Lausanne company announced CHF 5 million in a pre-Series A round led by Valquest Partners, with Bosch Ventures (Robert Bosch Venture Capital GmbH), industry angels and private investors. Fadi Noureddine of Valquest Partners joins the board.
The amount appears in two currencies, not two figures. The company's release says CHF 5 million, about EUR 5.4 million or USD 6.1 million by its own conversion. Startup Rise headlines EUR 5.4 million. Startupticker gives CHF 5 million.
The technology comes from EPFL. According to the company, Dr Stanislav Sergeev developed the principle there, published it in Nature Communications in 2023, and is now Sonexos's CTO. Sonexos holds an exclusive licence to the granted foundational patents in its field of use.
The claim: a software-controlled plasma layer, the Plasmacoustic Metalayer, absorbs sound at a surface and targets low-frequency hum from fans, compressors and motors. Prototypes reduced noise by up to 20 dB in ventilation systems and 16 dB in domestic appliances, under application-specific test conditions, according to Startupticker. These are the company's own prototype figures.
CEO and founder Mark Donaldson previously founded SoundChip, which was acquired by DSP Group.
The limits: no valuation is published, the paid integration programmes with appliance and HVAC manufacturers are not named, and the most advanced programmes target series production in early 2028, so no product is in series production yet.
What the money pays for: moving from engineered prototypes to qualified industrial products, including customer integration, reliability testing and qualification, and bigger engineering and applications teams.