Sonexos Raises CHF 5 Million to Bring Plasma-Based Noise Control to Series Production

Pre-Series A led by Valquest Partners, with participation from Bosch Ventures, will take solid-state noise control from prototypes to industrial production.

LAUSANNE, VAUD, SWITZERLAND, October 21, 2026 /EINPresswire.com/ — Sonexos SA, a Swiss deep-tech company developing solid-state active noise control, today announced CHF 5 million (approximately EUR 5.4 million / USD 6.1 million) in new equity financing. The Pre-Series A round was led by Valquest Partners, with participation from Robert Bosch Venture Capital GmbH (Bosch Ventures) and industry angels and private investors. Fadi Noureddine, Founder and Managing Partner of Valquest Partners, joins the Sonexos Board of Directors.

KEY HIGHLIGHTS
* Patented plasmacoustic technology absorbs low-frequency noise electronically in a thin panel format, overcoming the limitations of conventional passive treatments, from thick foam to heavy barriers, at low frequencies.
* Prototype systems have reduced low-frequency noise by up to 20 dB in HVAC systems, within the range of premium noise-cancelling headphones.
* Paid integration programmes with global appliance and HVAC OEMs; first series production targeted for early 2028.
* Expansion into AI data-centre cooling, where reduced fan noise could ease community concerns and help sustain cooling capacity under night-time noise limits.

Sonexos is developing a new way to address low-frequency noise from fans, compressors and motors. This is the persistent hum that carries through walls and windows, and the hardest noise to escape. Conventional acoustic treatments become increasingly bulky as frequencies fall and can restrict airflow. Loudspeaker-based active noise control, meanwhile, works well in the confined space of a headphone but struggles with the complex, three-dimensional sound fields of real-world applications. Sonexos’ patented Plasmacoustic Metalayer™ instead uses a software-controlled layer of plasma to absorb sound at a surface. The system is thin, lightweight and has no moving parts. Prototype systems have achieved low-frequency noise reductions of up to 20 dB in ventilation systems and 16 dB in domestic appliances, under application-specific test conditions.

The financing will support the transition from engineered prototypes to qualified industrial products. Sonexos is conducting paid prototype-integration programmes with leading global manufacturers of domestic appliances and HVAC equipment and advancing toward appliance-level design-in. Its most advanced programmes target series production in early 2028, subject to integration, regulatory compliance and new-product introduction.

“Engineers have always had to trade space and weight for silence. Plasmacoustics removes that compromise,” said Mark Donaldson, Founder and CEO of Sonexos. “This financing carries it from working prototypes into our customers’ products, at scale.”

“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, Founder and Managing Partner of Valquest Partners. “The combination of differentiated science, a strong intellectual-property position and progress with leading OEMs gives the company a credible path toward industrial production.”

“Technology is most valuable when it moves out of the laboratory and solves problems people experience every day. Sonexos is a strong example of that principle: outstanding deep tech addressing a very tangible challenge, with applications ranging from the appliances in our homes to the infrastructure powering the digital economy,” said Dr. Ingo Ramesohl, Managing Director of Bosch Ventures. “What convinced us in particular is the credible pathway toward industrial scale.”

The team and the technology

Sonexos was founded by Chief Executive Officer Mark Donaldson, who has spent three decades building companies in active noise control, including SoundChip, which developed noise-cancelling smart audio codecs for headphones and earbuds from leading consumer electronics brands and was acquired by DSP Group, now part of Synaptics. The foundational plasmacoustic technology is licensed from EPFL, where Dr. Stanislav Sergeev, now Sonexos Chief Technology Officer, developed the principle, published in Nature Communications in 2023. Chief Operating Officer Andrea Onetti joined after more than three decades at STMicroelectronics, most recently as Executive Vice President and General Manager of its MEMS Sub-Group, bringing extensive experience in industrialising semiconductor devices at very high volume.

Together, the team has developed the technology across three hardware generations, reducing system weight and volume by more than 80% while integrating plasma architecture, low-power high-voltage electronics and adaptive control software. Its aim is to extend active noise control from the space around the ear to entire products and installations.

The company’s Plasmapanel^® packages the actively controlled plasma metalayer into a sealed, inert-gas-filled module driven by proprietary low-power, high-voltage electronics. Depending on installation, Plasmapanel-enabled systems absorb sound from 30 Hz to 1,500 Hz and, compared with passive silencers of similar low-frequency performance, need less than a fifth of the space and weight. For OEMs, that frees room for more compact products or for features that bulky acoustic treatment would otherwise displace.

Building the route to production

Sonexos is developing an industrial ecosystem rather than manufacturing every component in-house. STMicroelectronics, which has named Sonexos a partner in its ST for Startups programme, is supporting development of low-power, low-cost electronics. A strategic collaboration with Vandewiele Group, through its subsidiary Roj, provides a route toward series manufacturing for European OEM programmes, including electronics production, box-build and cabling.

Sonexos will offer turnkey panels with integration support, as well as an enterprise model in which larger OEMs build the technology into their own products and production lines using Sonexos components, such as Plasmadrive™, and software.

A further opportunity in data-centre cooling

The growth of AI infrastructure is increasing demand for cooling, often delivered by large fans and dry coolers operating continuously. Low-frequency fan noise is difficult to screen, and as facilities grow, operators must balance the need for more cooling with their obligations to neighbouring communities. Where noise limits restrict night-time operation, quieter cooling could help operators maintain performance without adding airflow resistance.

Sonexos is developing the Plasmapanel Radial™ Active Silencer to mount around a fan discharge and attenuate low-frequency sound without obstructing the airflow path. In July 2026, the company announced a collaboration with Euronext Milan-listed SIT to integrate the technology with fan platforms for data centres, battery energy storage and industrial cooling. SIT is the first member of the Sonexos Certified Fan Partner Program; the companies plan to present a first working demonstrator at CES 2027.

Use of funds

The CHF 5 million will fund the industrialisation of the core platform; customer integration, reliability testing, qualification and regulatory compliance; the expansion of engineering and applications teams in Switzerland and internationally; and broader international protection of its intellectual property. Sonexos holds an exclusive licence from EPFL to granted foundational plasmacoustic patents in its field of use and has filed four further patent families of its own, with two UK patents granted and applications pending in other major markets.

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About Sonexos SA

Sonexos SA is a Swiss technology company pioneering solid-state plasmacoustic solutions for active noise reduction. Its patented Plasmacoustic Metalayer platform enables electronically programmable control of sound, allowing compact, lightweight and energy-efficient management of low-frequency noise in domestic appliances and HVAC, and in industrial, infrastructure, automotive and specialised acoustic applications. The company’s Plasmapanel and Plasmadrive technologies are designed to overcome the practical limitations of conventional passive acoustic materials and traditional active noise control systems. www.sonexos.com

About Valquest Partners

Valquest Partners is an independent private investment and asset management firm. Founded in 2013, the firm specializes in sourcing, shaping, and scaling venture capital and private equity investments. Valquest Partners focuses on high-quality, long-life assets primarily within the Energy, Power, MedTech, and Industrial Biotech sectors, with over a decade in bridging the critical gap between deep technological innovation and commercial viability. Headquartered in Limassol, Cyprus, with additional operations in Beirut, Lebanon, and Luxembourg, the firm manages an investment portfolio concentrated across Europe and the Gulf Cooperation Council (GCC) region. www.valquestpartners.com

About Robert Bosch Venture Capital GmbH

Robert Bosch Venture Capital GmbH (Bosch Ventures) is the corporate venture capital company of the Bosch Group, a leading global supplier of technology and services. Bosch Ventures invests worldwide in innovative start-up companies at all stages of their development. Its investment activities focus on technology companies working in areas of business of current and future relevance for Bosch, above all, automation and electrification, climate technologies, enabling technologies, and healthcare systems. Bosch Ventures also invests in services and business models that are relevant to the above-mentioned areas of business. Furthermore, Bosch Ventures enables co-innovation between Bosch and startups through the Open Bosch Program. www.bosch.ventures

Notes to editors

Product, integration, team and founder images, captions and technical background are available in the Sonexos media kit. Performance figures refer to different prototype tests and comparisons; results vary by installation and test conditions and do not imply uniform attenuation across the stated frequency range.

Mark Donaldson
Sonexos SA
+41 78 612 44 79
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