2.7. Sample Preparation and Data Collection

Several samples with the specifications shown in Table 1 were tested using the device designed in this work. Before each measurement, the cuvette is filled with 4 mL of a specific sample and inserted inside the cuvette holder, the top side of the device is closed using a sliding lid, and then the user can interact with the system through the keypad and the LCD. Once the user turns on the device, a message will be displayed on the LCD to ask the user to start. The device operates by allowing the user to add the list of liquids he wants to identify based on the application of interest (i.e., food, industry, pharmaceutical and so on). A sample is inserted in the cuvette to allow the system to recognize it and store its corresponding values with its particular nickname so it can be recognized later on. To ensure good selectivity and repeatability, the measurement for each sample was repeated three times and in every test, the device was able to recognize the sample.

Specific samples can be added to the list and stored in the memory of the device. Once the device is turned on, the LCD will display a message to ask the user to start measurement by pressing the hash button #. If he pressed 0 that means he wants to do calibration based on an already stored list of liquids. If he pressed 1 that means he wants to enter a new sample to the list and give it a label to distinguish it from other samples. Finally, if he pressed 2 that means he wants to identify a sample based on a stored list of samples.

The raw data from photosensors are received through the analogue pins and processed to extract the absorption of the specimen that is used as a fingerprint or signature to identify the material inserted. The measured data is controlled using an Arduino Mega 2560 programmed in the C language through IDE software. The code that we have written to program our device, as well as a short video to show the device running are included in the following link: https://yarmoukuniversity2014-my.sharepoint.com/:f:/g/personal/yusra_obeidat_yu_edu_jo/EmYzvuN7fzpAq2DX7gpLc24BvVklPbO1D8jatgIcgcmgQw?e=SD8a8b.