Smartphone Biosensors Go Straight To DVD

Lei Li of Washington State University has been captivated by the idea of using smartphones to perform spectrophotometry since researchers at the University of Illinois, Urbana-Champaign (UIUC), introduced it a few years ago. Because smartphones are ubiquitous and inexpensive compared with conventional analytical instruments, smartphone spectrometers are promising tools for performing biosensing assays and medical diagnostics outside the clinic or laboratory. Li and his team are working to make these smartphone devices even more accessible with an assist from another cheap and common technology—the DVD (ACS Sens. 2016, DOI: 10.1021/acssensors.5b00204). UIUC-style smartphone spectrometers rely on diffraction gratings to spread white light into a rainbow spectrum before entering a phone’s camera lens. That spectrum can then be used in spectroscopic assays, such as ELISA. But commercial glass diffraction gratings cost around $100, Li says. Plastic chips cut from $1.00 DVDs can diffract light into useful spectra, the team demonstrated. The researchers spiked cuvettes of tap water with paraoxon and showed that their platform could detect the toxin at nanomolar concentrations, which is comparable to the performance of commercial instruments, Li tells C&EN.