This thesis describes work to investigate the potential of using an ordinary mobile phone to perform chemical sensing by colorimetric analysis of reflected light. The wide availability and familiarity of mobile phones make them excellent devices for aiding consumers in making on site tests in their everyday lives. A major part of the work has been the development of the necessary software to be able to use a standard mobile phone to study diffuse reflection with the screen as illumination source and the front view camera for collection of spectral information. Java Micro Edition was used to control the hardware resources of the phone. The NetBeans 6.5 platform facilitated the design, development, testing and implementation of a dedicated Mobile Information Device applet for performing the necessary tasks associated with controlling the screen light and recording the reflected light intensities. MATLAB was employed to extract spectral information from the recorded images. Initially, tests with a virtual sample having areas with different colors were performed. Optimization of the alignment of the sample and the distance between the camera and the sample were carried out and the influence of ambient light was investigated. The lateral resolution of the images enables optical readout of sensor arrays as well as arrays for diagnostics. The potential of using the technique for direct measurement of properties related to the quality of drinking water, food and beverages was also investigated. Liquid samples were prepared in deionized water. Colored compounds such as iron(III)chloride and humic acid in the concentration range 2-10 mg/l were classified from their reflected intensities. Colorless arsenic(III) was analyzed by its bleaching reaction with iodine/starch. An alternative arsenic detection method based on measurement of discoloration of iron containing sand was demonstrated. We have also demonstrated that mobile phones can be used for qualitative analysis of food and drink, such as cold drinks, meat, vegetables and milk in terms of general food quality.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:liu-65733 |
| Date | January 2011 |
| Creators | Iqbal, Zafar |
| Publisher | Linköpings universitet, Institutionen för fysik, kemi och biologi, Linköpings universitet, Tekniska högskolan, Linköping : Linköping University Electronic Press |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Licentiate thesis, comprehensive summary, info:eu-repo/semantics/masterThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Linköping Studies in Science and Technology. Thesis, 0280-7971 ; 1505 |
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