BGF joins $19m investment in respiratory diagnostics firm TidalSense

BGF has completed a follow-on investment in Cambridge-based TidalSense, a company using AI to transform respiratory diagnostics, particularly for conditions such as Chronic Obstructive Pulmonary Disease (COPD). The funding will accelerate commercialisation in the UK & Ireland, and Europe, and support market entry to the USA as TidalSense fields inbound interest from over 60 countries.

At least 600,000 people in the UK are currently waiting for a formal COPD diagnosis. The test they are waiting for – spirometry – requires forceful exhalation, specialist training to administer, and can take the best part of an hour per patient when factoring in wait and recovery time.

TidalSense has built an alternative. N-Tidal Diagnose requires patients to breathe normally into a handheld device for 75 seconds, capturing a CO₂ waveform — a capnogram — of the kind traditionally used in critical care, which a set of AI models analyses to detect COPD. Any healthcare professional can be trained to use the device in 10 minutes, with no specialist qualification required. The result: clinicians can see 4-6 patients an hour, compared to roughly one an hour with traditional spirometry.

COPD is the UK’s third biggest cause of death, killing around 30,000 people a year and costing the NHS £1.9 billion annually. Over half of NHS regions’ lack the capacity to meet current demand for spirometry testing, and an estimated 1.9 million people are living with the condition — diagnosed and undiagnosed combined. COPD is the second-leading cause of emergency hospital admissions, while an exacerbation serious enough to require hospital treatment is linked to worse prognosis and higher risk of death.

Dr Ameera Patel, CEO of TidalSense, said: “Respiratory disease has been neglected by governments and health systems for years, often overshadowed by cancer and cardiovascular disease, even though it affects one in five people. That’s finally starting to change. The World Health Organization now recognises COPD as a global health priority, and it’s about time. Part of the problem has always been how we talk about it: COPD is widely seen as a smoker’s disease, but a quarter of cases come from air pollution and the biomass fuel millions still cook with every day.”

“We’re still diagnosing in the 21st century with a test invented in the 1800s, and one that needs specialist equipment and training most of the world doesn’t have access to. Lower income and minority communities pay the price for that first. That’s the gap we want to close at TidalSense, and the NHS is the first place we’re doing it.”

N-Tidal Diagnose was designed to close that gap. Its AI diagnostic models have been trained on more than 2.5 million patient breaths. The patented technology is the product of more than a decade of R&D that has been led by some of the leading experts in the field. In the first post-market validation of the device — presented at the European Respiratory Society congress in 2025, and conducted on a completely unseen patient cohort — N-Tidal Diagnose achieved above 90% performance across all key metrics of diagnostic accuracy.

N-Tidal Diagnose software became the first non-spirometry AI diagnostic device to receive a CE mark under EU MDR (Class IIa) for COPD in March 2025. and launched into the NHS in September 2025. It was commissioned by Suffolk and North-East Essex Integrated Care Board, and its use has since expanded into NHS Wales, community lung screening clinics in the South of England, and now into Glasgow.

BGF initially invested in TidalSense in December 2020, to fast-track development of its award-winning N-Tidal device. Since then, BGF has completed several follow-on investments to support the medtech innovator’s growth journey.