There are many factors that can alter one’s reaction to drugs or medicines. In most cases, clinical trials prior to the launch to the market of new drugs take these factors into account to create a dose that causes the desired effect on the bulk of the population. This dose is known as “effective dose”; however, a small percentage of people may present a higher sensitivity to a certain substance, so, for them, an effective dose could trigger damaging unwanted effects or even cause death. Here we report a microfluidic device based on Interfacial Cell Cytometry (iCC) to determine the Lethal Concentration (LC) of a substance for different individuals. This technique consists in the creation of an array of protein islets for single-cell adhesion, patterned by a technique called Micro-Contact Printing or μCP. This technique enables the quantitative measurement of cell adhesion to a substrate before and after any stimuli. In this project, a single-cell adhesion method has been developed for the attachment of Mesenchymal Stem Cell (MSC) in a device to evaluate the effect of drugs, medicines, poisons or other toxic substances on cells taken from the very patient or corpse, being of use in both biomedical research and forensic sciences as an approach to personalized medicine