Sensors and Actuators B 239 (2017) 571–577 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb A smartphone based surface plasmon resonance imaging (SPRi) platform for on-site biodetection Hasan Guner a , Erol Ozgur a , Guzin Kokturk b , Mehmet Celik c , Elif Esen b , Ahmet E. Topal a , Sencer Ayas d , Yildiz Uludag b , Caglar Elbuken a , Aykutlu Dana a,∗ a UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey b UEKAE-BILGEM, The Scientific and Technological Research Council of Turkey (TUBITAK), Gebze, Kocaeli, 41470, Turkey c Department of Computer Engineering, Middle East Technical University, Ankara, 06800, Turkey d Canary Center at Stanford for Cancer Early Detection, Department of Radiology, Stanford School of Medicine, Palo Alto, CA 94304, USA a r t i c l e i n f o Article history: Received 2 July 2016 Received in revised form 5 August 2016 Accepted 10 August 2016 Available online 10 August 2016 Keywords: Plasmonics Surface plasmon resonance imaging Optical discs Mobile sensing Biosensors Optical sensor a b s t r a c t We demonstrate a surface plasmon resonance imaging platform integrated with a smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are pro- duced by metal coating of commercial Blu-ray discs. A compact imaging apparatus is fabricated using a 3D printer which allows taking SPR measurements from more than 20.000 individual pixels. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 × 10 −5 RIU which is comparable with the detection performance of commercial instruments. As a demonstration of a biological assay, we have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications. © 2016 Published by Elsevier B.V. 1. Introduction The wide use of mobile phones all across the world created significant opportunities for healthcare applications using mobile devices. Improvement of healthcare services requires democ- ratization of the services with higher quality and lower cost. Early diagnosis, close monitoring, patient comfort are some of the concerns that healthcare providers are striving to improve on. The development of lab-on-a-chip platforms in the last two decades brought several examples of novel platforms that can be used for rapid diagnosis of widespread diseases. Portability, short turn-around-time, cost-efficiency and connectivity are some of the critical assets that successful devices should possess. The advancements in such areas enabled the use of lab-on-a-chip sys- tems as on-site or point-of-care systems not only for remote or resource-limited settings, but also for home-monitoring of elderly population at developed countries. One of the main bottlenecks in transforming the lab-on-a-chip systems into point-of-care diagnostic devices is the requirement to miniaturize and combine several off-chip components. The mar- ∗ Corresponding author. E-mail address: aykutlu@unam.bilkent.edu.tr (A. Dana). riage of the lab-on-a-chip systems with mobile phones was the tipping point that yielded a plethora of integrated screening and diagnostic devices. Mobile phones provide powerful CPUs, touch screen displays, advanced connectivity features as well as high pixel-count, sensitive cameras and integrated light sources. There- fore, the use of mobile phones for applications requiring optical detection is an interesting and rapidly developing field of research. For instance, immunodiagnostic assays, lateral flow assays, micro- scopic imaging, flow cytometry, colorimetric detection, photonic crystal and surface plasmon resonance (SPR) based biosensing have been demonstrated using mobile phone platforms [1–12]. In this study, to the best of our knowledge we present the first surface plasmon resonance imaging on a smartphone. SPR biosensing is a popular method for quantitative anal- ysis and characterization of biomolecular interactions [13–15]. SPR provides label-free and real-time detection of binding events with high sensitivity. Surface plasmons are electromagnetic waves propagating along and evanescently decaying away from the metal/dielectric interface. This field confinement around the boundary makes plasmon resonance coupling condition extremely sensitive to the local refractive index changes caused by specific adsorption of target analytes onto the molecular probes residing on the metal surface. Recently, some studies have demonstrated SPR sensing using smartphone. Preechaburana et al. reported angle- http://dx.doi.org/10.1016/j.snb.2016.08.061 0925-4005/© 2016 Published by Elsevier B.V.