Paper-based Analytical Devices

In spite of great achievement in analytical instrumentation, developing inexpensive portable analytical platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings, have attracted a significant interest. Current analytical devices are very complex and expensive, need well-trained operator, consume expensive and harmful chemicals and last but not least have limitation for in-field applications. Lab-on-a-chip analytical devices and micro total analysis systems are relatively new group of analytical tools, capable of analyzing complex within one analytical run.Paper-based analytical devices (PADs), as a promising and powerful platform, have shown great potential in the development of POC tests. There are a lot interests on using paper as a substrate for development of analytical devices since paper is very cheap, has self-pumping capability because of capillary action, it’s surface can be modified easily and is available in different forms and shapes. Microfluidic PADs (PADs) and colorimetric sensor arrays (or optoelectronic noses) are emerging methods that use paper as substrate.Since 4 years ago, my research group has directed its research priority toward development of paper-based analytical devices for applications in food, environment and health. In this seminar, I will present the results of the works done or under investigation in my research group regarding paper-based analytical devices. We used paper substrate in development of optoelectronic noses for ultrasensitive determination of volatile organic compounds (VOCs) and used them for authenticate investigation of herbal distillates producing in Shiraz and detection of adulteration in natural vinegars [1,2]. Concerning PADs, we used simple patterning methods to fabricate hydrophilic microchannels on the paper. These microchannels can automatically flow the liquid samples, mix them and allow chemical reactions to take place at the end. A simple PADs device was fabricated based on molten paraffin and was then used for colorimetric measurement of acidity constant of indicators [3]. We used electrochemically integrated PADs for fabrication of an electrochemical concentration cell, which is able to measure highly concentrated ammonia solutions in petrochemical industries. Also, PADs were used for fabrication of bipolar electrochemical cells based on colorimetric measurments.