Portable paper-based device for ABO and RhD typing using smartphone interpretation: Optical answer sheet reading concept.

The slide method for ABO blood group typing is commonly used for mobile blood donation and field applications because the test is easy, cost-effective, can be completed in a few minutes and requires a small volume of reagents. However, the reaction must be observed by an individual with expertise within 2 min; otherwise, drying of the reagent will give a false positive result. Moreover, the blood typing reagents must be stored at 4 °C. The present study aimed to create a paper-based device for ABO and RhD blood typing and combine an optical answer sheet reading concept to read and interpret the results with Android smartphones. The invention of this device involved the use of simple filter paper and conjugate pads that were treated with anti-A, -B and -D antibodies. Blood type can be visually identified from the detection zone at the end of the filter paper. An Android smart phone was designed to read the detection zone, interpret the data and subsequently report the results on the user's smartphone. A helpful color chart was also designed for blood typing interpretation by the naked eye. The use of smartphones can reduce human error in data reading and interpretation. In conclusion, ABO and RhD typing with paper-based devices using a smartphone interpretation may provide further advantages for home-based users, mobile blood donation sites and field applications.