Smartphone-Enabled Personalized Diagnostics: Current Status and Future Prospects

Abstract

Smartphones are becoming increasingly versatile thanks to the wide variety of sensor and actuator systems packed in them. Mobile devices today go well beyond their original purpose as communication devices, and this enables important new applications, ranging from augmented reality to the Internet of Things. Personalized diagnostics is one of the areas where mobile devices can have the greatest impact. Hitherto, the camera and communication abilities of these devices have been barely exploited for point of care (POC) purposes. This short review covers the recent evolution of mobile devices in the area of POC diagnostics and puts forward some ideas that may facilitate the development of more advanced applications and devices in the area of personalized diagnostics. With this purpose, the potential exploitation of wireless power and actuation of sensors and biosensors using near field communication (NFC), the use of the screen as a light source for actuation and spectroscopic analysis, using the haptic module to enhance mass transport in micro volumes, and the use of magnetic sensors are discussed.

Keywords: biosensors; molecular methods; point of care devices; smarthphone-based diagnostics.

Figure 1

Point-of-care devices are two-part systems targeting professional and personal users. Mobile devices have the potential to replace dedicated instrumentation and lead to a new wave in personalized diagnostics. At the same time, the consumable part will adapt to this new paradigm. The left-hand side features Abbott’s i-Stat system and consumables, and Abbott Freestyle Libre and its biosensing capsule. The right-hand side illustrates the potential use of mobile devices, such as smartphones and smartwatches, to accomplish POC biosensing.

Figure 2

Summary of the main actuation and detection modes currently available in smart personal devices.

Figure 3

Light spectra from an iPhone 7. Top: LED flashlight. Bottom: individual spectra obtained from the screen emitting red (255,0,0), green (0,255,0), and blue (0,0,255) light. The inset shows the spectra obtained from a white (255,255,255) screen.

Figure 4

Haptic voltammetry. Cyclic voltammetry of 1 mM ferrocyanide in 0.1 M KNO₃ at a 2.5 mm screen-printed graphite disk electrode (scan rate 25 mV s⁻¹), shaken by a ringtone vibration (Haptic CV) and without vibration (quiet CV). The labeled points highlight the instant when the vibration starts or stops. Total solution volume was 60 μL.

Figure 5

(a) Design of the smartphone microscope reported by Rivenson et al. 2018 (adapted with permission from [63]; copyright 2018 American Chemical Society). (1) Photography of the device taken from different views and (2) schematic illustration of its components. (3) Image of a USAF test resolution chart captured using the smartphone-based microscope. The smallest line width that is resolved is ~0.87 μm. (b) Design of the mobile phone fluorescence plate reader described in Kong 2017 for measuring LAMP DNA amplification carried in a 25-well plate (adapted with permission from [64]; copyright 2018 American Chemical Society). (1) Assembly of the mobile reader device and (2) schematic side view showing inner structure. The phone is assembled in a custom-designed 3D-printed optomechanical interface where the microtiter plate is inserted. An array of 5 × 5 blue LEDs was used as the excitation light source for fluorescence, filters were placed above and below the plate, and the fluorescence signal was collected by 75 optical fibers (3 per well) and imaged by the smartphone camera via a single lens. (3,4) Real photographs of the device. (5) Example of fluorescence image obtained by the random optical fiber pattern and corresponding well positions on the right.