Smartphone spectroscopy: three unique modalities for point-of-care testing

Abstract

Here we demonstrate three principle modalities for a smartphone-based spectrometer: absorption, fluorescence, and photonic crystal (PC)-based label-free detection. When combined with some simple optical components, the rear-facing CMOS camera in a mobile device can provide spectrometric data that rivals that of laboratory instruments, but at a fraction of the cost. The use of a smartphone-based platform poses significant advantages based upon the rise of smartphone apps, which allow for user-interface and data-processing algorithms to be packaged and distributed within environments that are externally maintained with potential for integration with services such as cloud storage, GIStagging, and remote expert analysis.We demonstrate the absorption modality of our device by performing an enzyme-linked immunosorbent assay (ELISA) on both a cancer biomarker and a peanut allergen, demonstrating clinically relevant limits of detection (LOD). Second, we demonstrate the success of a molecular beacon (MB)-based assay on the smartphone platform, achieving an LOD of 1.3 pM for a specific RNA sequence, less than that of a commercial benchtop instrument. Finally, we use a PC biosensor to perform label-free detection of a representative biological interaction: Protein A and human immunoglobulin G (IgG) in the nanomolar regime.Our work represents the first demonstration of smartphone-based spectroscopy for biological assays, and the first mobile-device-enabled detection instrument that serves to measure three distinct sensing modalities (label-free biosensing, absorption spectroscopy, and fluorescence spectroscopy). The smartphone platform has the potential to expand the use of spectrometric analysis to environments assay from the laboratory, which may include rural or remote locations, low-resource settings, and consumer markets.

Point-of-Care Diagnostics: Recent Developments in a Connected Age

“…These assays typically require spectrophotometers, fluorometers, or plate readers which are expensive and bulky. To bridge the gaps between high-resource central laboratories and smaller, lower-resource clinics where the ability to expand diagnostic testing capabilities is desirable, many groups have worked on developing miniaturized smartphone spectrometers which use detection modalities of absorption, fluorescence, or photonic crystal-based detection. − Most of these methods report single channel detection or one sample monitoring per measurement. To increase sample throughput, an 8-channel smartphone spectrometer suitable for 96 well plates was developed, which included a cradle to hold the smartphone and a custom app to control optical sensing parameters and to align each sample to the corresponding channel .…”

“…This system features onboard analysis to make it easy-to-use. In another example, the MinION device from the company Oxford Nanopore Technologies is a pocket-sized sequencer, with an array of nanopores to conduct sequencing . There have also been announcements to introduce other platforms (such as the SmidgION and PromethION) which could be appropriate for some of the use cases described in this Review.…”