Create a technical diagram of a droplet digital PCR (ddPCR) system: sample partitioning into ~20,000 nanoliter-scale water-in-oil droplets via microfluidic droplet generator, thermal cycling of droplet emulsion in standard 96-well plate, endpoint fluorescence reading of each droplet (FAM and HEX channels), positive/negative droplet classification by amplitude threshold, Poisson statistics for absolute copy number quantification without standard curve. Show the microfluidic chip cross-section and droplet formation mechanism.
