A series of electrodes and a machine learning system are configured to detect changes in biological tissue over time. Specifically, the system may include a wearable device configured to detect changes in tissue response to an electrical signal that may be indicative of cancerous tissue, e.g., breast cancer and/or other types of cancer. The system optionally combines measurements from bioimpedance sensors, miniaturized ultrasound arrays, temperature sensors, and/or printed microwave planar antenna to detect changes in breast tissue composition and vascularity. The system may also be used to detect other physiological states such as menstrual cycles and/or various conditions related to hydration or breathing patterns.