The 9 startups VCs are buzzing about from YC's latest Demo Day

Another Y Combinator Demo Day took place Thursday, and this batch skewed more toward deep tech than in past years. TechCrunch asked early-stage VCs to name the buzziest startups, compiling a list of companies flagged by at least two investors — though valuations, investors said, were more grounded than in recent cohorts.

Several standouts target the AI industry’s power and hardware bottlenecks. Atomarine, co-founded by an MIT computer-science-and-naval-engineering graduate and an MIT nuclear-engineering PhD student, wants to put data centers on barges at sea, using seawater for near-free cooling; it plans a gas-powered pilot by 2028 before shifting to floating nuclear power ships in 2032, and claims it has secured more than $4 billion in customer interest through letters of intent — helping make it one of the batch’s highest-valued startups, according to one VC. Dipole Labs built an optical switch that keeps data moving between GPUs as light rather than converting it to electricity and back, aiming to cut the power and heat lost in that conversion. Lamb Labs, co-founded by an Imperial College London AI PhD and an Oxford theoretical physicist, wants to hardcode AI model weights directly into silicon chips it calls “Model Processing Units” to eliminate memory-bandwidth bottlenecks during inference.

Defense and physical-world startups also drew attention. Isengard Industries, co-founded by a former Australian Army officer and an entrepreneur who previously scaled a Ukraine-focused drone startup to $60 million in revenue, aims to mass-produce jet-powered strike and counter-drones within allied countries at a fraction of prime-contractor prices; it says it’s already generating $10 million in revenue and has drawn some of the batch’s loftiest valuations, according to two investors. Praxis Robotics partners with businesses to collect video and data of humans working, turning it into training material for robotics companies, and says it has captured data across more than 150 environments. Cosmic Robotics, aiming eventually to help build a city on Mars, builds autonomous robots for heavy-duty tasks like installing solar panels and says it holds $25 million in contracts through 2027.

Consumer-facing bets rounded out the list. Nori, launched six weeks before Demo Day, sells a $1,600 humanoid robot that helps clean and fold clothes — far cheaper than robots like Neo, priced around $20,000 — and already claims nearly half a million dollars in sales. Parasma is exploring training human brain cells as an energy-efficient alternative to conventional AI computing hardware. Waddle Labs, founded by Harvard graduates, built a layer of LLM agents that write and check robot control code from natural-language instructions, positioning itself as “Claude Code for robotics.”

Why it matters

The batch’s tilt toward deep tech and defense — alongside VCs’ insistence that valuations are more disciplined than in recent years — suggests investors are trying to fund harder physical-world problems without repeating the frothy pricing of earlier AI cohorts.