PCR’s three speed bottlenecks (diffusion, polymerase rate, ramp speed) are already so well-optimized that photonic PCR offers only modest real-world gains.
Key Takeaways
Swapping Taq for Phusion polymerase cuts extension time from 1 min/kb to 15 sec/kb – a larger win than any thermocycler hardware upgrade.
Reducing cycle count below 30 backfires: “product reannealing” makes amplified strands outcompete primers, degrading yield before reagents run out.
2009 IR-laser-on-mineral-oil and 2015 UC-Berkeley gold-film-plus-LED designs both hit 30-40 cycles in ~6 minutes, roughly 2x the ramp rate of commercial machines.
A sub-$50 photonic PCR build (“Utah” Hans, gold film + LEDs) and a black-tube laser device (Sebastian Cocioba) each received $3,500 Astera Institute microgrants.
When using Phusion at fast ramp rates, the extension step still consumes ~two-thirds of total cycle time, so near-instant ramp rates compress only the smaller fraction of total run time.
