The needs of an ever growing human population are fueling demands for better and cheaper sensors for the early detection of harmful chemicals, pathogens and diseases markers from a variety of sources such as food, water, bodily fluids and contaminated surfaces. To address this, recent innovations utilize Microelectromechanical Systems (MEMS) technology to integrate multiple laboratory functions onto millimeter-sized chips to form Micro Total Analysis Systems (µTAS) or Lab-on-chip (LOC) devices. While sophisticated and powerful, the use of these devices for chemical and biological sensing is limited by complicated fabrication processes, high cost and robustness of the sensors.

In this work we have developed a simple and inexpensive but exceptionally sensitive portable chemical and biological sensing platform through the innovative use of paper combined with Surface Enhanced Raman spectroscopy (SERS). Paper is functionalized with plasmonic nanostructures to transform it into a SERS substrate, while the natural properties of paper are leveraged for sample collection, cleanup, and analyte concentration in user-friendly formats such as wipes, dipsticks, and filters. The use of simple deposition methods such as inkjet printing for sensor fabrication combined with paper as the construction material means that sensors can be made at a very low cost. Additionally, the ability to be printed on demand eliminates issues with sensor shelf-life, while the absence of mechanical components makes these paper sensors much more robust than conventional sensors. In this work, practical applications of paper SERS sensors for the detection of food contaminants, narcotics, pesticides and other chemicals at trace levels are presented. Paper SERS sensors, by virtue of their low cost, simplicity of fabrication, high sensitivity and ease of use, promises to make chemical and biological sensing more accessible to the common user.