In this work, we develop a portable measurement system to detect the critical UV dose for cells, and we can make precautions to prevent people from skin cancer. In this research, we have developed a rapid and highly selective array using field-effect-transistor-based biosensor to monitor the real time electrical signal change of cell membranes. According to the difference of the electrical response, it is possible to predict when cells are undergoing apoptosis dynamically. All in all, our sensor can detect the signal change of cells when they are stimulated by outside environment.