A form of cancer therapy that uses electric fields to stop malignant cells from spreading remains controversial, because it's unclear how effective and safe it truly is. This coin-sized device developed by MIT's research center in Singapore, however, could help scientists study its effects more closely. What's more, it could eventually be used to personalize the treatment for each individual. Medical experts simply have to inject a mixture of hydrogels, healthy cells and different types of cancer cells taken directly from a patient into the device before subjecting it to electric fields at different frequencies. By doing so, they'll be able to pinpoint the most effective electric field frequency to use to treat that particular patient.