We describe a technique for the rapid ab-initio discovery of target-tailored tumoricidal DNA oligonucleotides inside an Illumina sequencing chip. By sequencing oligonucleotide pools we generate a physical microfluidic map of hundreds of millions of potential oligo clusters, in which every cluster is mapped to a specific set of spatial coordinates. Tumor cells, pre-loaded with a fluorogenic reporter of apoptosis, are then injected into the chip and monitored over time. Apoptotic tumor cells are identified and analyzed across the entire map, automatically revealing the coordinates of oligos that induced this effect. We demonstrate this method by identifying, within just a few hours, new oligos capable of directly and selectively inducing apoptosis in primary human tumor cells. Such a major capability could lead to a new paradigm of personalized cancer therapy.