A lab-on-a-chip (LOC) needs to be a disposable technology, to ensure a pristine chamber is available each time for precise measure of a sample. How can complex integrated photonics components like ring resonators be casually sacrificed in such one-time-only use? The answer lies in integration: photonic-based LOCs can be fabricated as a tiled array of many identical chips, on a flat silicon-based wafer. Why would this reduce the cost per unit chip? How would the cost of a penny-sized chip be influenced by production run expense, number of wafers used per run, and wafer size? Which of these factors seem to be more important for mass manufacturing?