CSignum, a Scottish start-up that sends sensor data through water and ground, has raised £2.6 million and appointed a new chief executive. The round, announced on 23 September, came from Archangels, PXN Ventures, Scottish Enterprise, the British Business Bank and a group of US angel investors, and follows a £6 million raise in April 2025.
John Nicholls, whose background spans international sales, fundraising and acquisitions in photonics, quantum, space and semiconductors, takes over as CEO, while Jonathan Reeves moves to chief strategy officer. The money is going into commercial expansion and scaling up manufacturing at the Bathgate company, founded in 2020, which also has offices in the US and the EU.
The problem CSignum is selling into is simple to state. Almost all IoT stops at the waterline.
The Blind Spot Below The Surface
That is because the radio signals behind mobile networks, Wi-Fi and low-power networks such as LoRaWAN fade quickly in water and soil, so a sensor on a riverbed or inside a buried structure has no easy way to report. We explained how those low-power networks normally reach devices in our guide to LPWAN, and all of them assume open air.
The usual workarounds each carry a cost. Sound-based underwater modems struggle with background noise and with signals bouncing off the surface, light-based links fail in murky water, and cables have to be dug in, can snag, and are easy targets for theft and vandalism on a public riverbank.
CSignum’s answer is what it calls electromagnetic field signalling. In plain terms, it pushes data through water, ice, soil, rock and concrete using an electromagnetic field rather than ordinary radio waves or sound, and the company says the signal crosses from water into air without the reflection that troubles sound-based systems. Its EM-2 product line claims two-way links of up to 200 metres.
In a river, that means a sensor pack on the bed can pass its readings to a unit on the bank up to 100 metres away, which then connects to a normal network. Nothing needs to be cabled across the bank, and nothing valuable has to sit in plain sight.
England’s Rivers Are Creating The Demand
Rivers are where the business is growing fastest, thanks to a law. Section 82 of England’s Environment Act 2021 requires water companies to monitor water quality continuously upstream and downstream of every storm overflow and sewage works discharge, tracking dissolved oxygen, ammonia, turbidity, temperature and pH.
The scale is large. Engineering consultancy RPS estimates about 27,500 discharge points fall under the rule, though outlets close together can share monitors, and the rollout, which falls in the water industry’s current 2025–2030 spending period, runs through 2035.
RPS also lists the practical obstacles, and they read like CSignum’s sales pitch: finding sites with power and a mobile signal, getting access to private land, and keeping sensors maintained and accurate between site visits. CSignum says UK water utilities already use its systems to monitor storm overflows under the rule. “CSignum exists to close the communications gap between inaccessible parts of the physical world and digital and AI systems,” Nicholls said.
Beyond The Riverbank
That gap extends well past English rivers, and the company is testing how far. Current projects include a smart buoy in the Gulf of Mexico and through-ground sensing for critical infrastructure in Asia, and CSignum has previously pitched its technology for monitoring ship hulls and guarding underwater assets at offshore wind farms and oil and gas platforms.
Each of those markets shares the same headache as the riverbed: valuable data sitting somewhere a normal wireless signal can’t reach, and a cable that is expensive or risky to run. We looked at how industrial sites stitch together different kinds of links in our industrial connectivity explainer, and CSignum is effectively offering one more link for the places the others can’t cover.
What The New Money Has To Prove
Covering those places at scale is the next test. “CSignum continues to make strong commercial progress, and this investment reflects our continued confidence in the team and the technology,” said Dan McKiddie of Archangels, which also backed the 2025 round.
Our read: handing the top job to a commercially focused CEO, and spending on manufacturing, signals that the company sees its main challenge as selling and building in volume rather than proving the physics. That is the right problem to have, but a £2.6 million round is modest for a hardware business with ambitions on three continents.
There are also limits the company doesn’t yet spell out. It publishes range figures but not data rates, which suggests the technology is suited to regular sensor readings rather than heavy data such as video. The open question is whether that is enough to win thousands of England’s river sites before cheaper cabled and sound-based options catch up, and whether the same kit can then travel beyond the UK’s regulatory tailwind.
