Fig. 4: Various thermal cycling technologies based rapid PCR.

a Joule heating, when electrical current passing through a resistive metal generates heat owing to electron collisions (M: metal atoms, e^-: free electron). b Joule heater-integrated lateral flow PCR kit, and c 30 cycles of a NiCr thin film-based Joule heater adapted from ref. ⁷⁵. d Thermoelectric heating uses Peltier-elements, in which, when a voltage is applied, heat is absorbed at the n-type material and dissipated at the p-type material, enabling precise temperature control. e Peltier-element-based thermocycler, and f temperature profiles of Peltier-element-based thermal cycler, reprinted with permission from ref. ⁷⁹, Elsevier, g Plasmonic heating, when light strikes a metallic nanoparticle, the oscillating electric field of the light induces a collective oscillation of the conduction electrons within the nanoparticle. During the damping process of these oscillations, hot electrons are generated as the energy from the plasmons transfers to the electrons. These hot electrons subsequently lose their energy through electron-phonon interactions, converting it into localized heat, which results in significant temperature increases near the surface of the nanoparticle. h Plasmonic optical wells (POWs) based photothermal conversion effect, and i temperature profiles, reprinted with permission from ref. ⁸⁴, American Chemical Society