AbstractThe conventional method of blood grouping, reliant on antigen-antibody reactions, entails invasive blood sampling and is susceptible to time-consuming procedures and potential mismatches, leading to severe consequences during transfusions. This study endeavors to develop a non-invasive human blood type detector, assessing spectral responsivity relative to blood types and comparing it with conventional methods. A cross-sectional descriptive study involving 120 participants was conducted, with the spectral responsivity serving as the dependent variable. The non-invasive detector, comprising input (power supply, OPT101, IR LED), processing (Arduino), and output (LCD Display) components, was employed. Participants, meeting inclusion criteria of healthy adults aged 18-50 with blood typing records, underwent trials using the setup, excluding those under anticoagulant medication, pregnant, or with blood cancer. Subjects placed their middle finger into the setup for comfortable positioning, un.....