   Paper‐based titration algorithm                                                                                                                                                                                                                                                                                                                                              Paper‐based titration algorithm                                                                                                                                                                                                                                                                                                                                                                                                         Paper‐based titration algorithm                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Self‐titration 