From Sophisticated Analysis to Colorimetric Determination: Smartphone Spectrometers and Colorimetry

Smartphone-based spectrometer and colorimetry have been gaining relevance due to the widespread advances of devices with increasing computational power, their relatively low cost and portable designs with user-friendly interfaces, and their compatibility with data acquisition and processing for “lab-on-a-chip” systems. They find applications in interdisciplinary fields, including but not limited to medical science, water monitoring, agriculture, and chemical and biological sensing. However, spectrometer and colorimetry designs are challenging tasks in real-life scenarios as several distinctive issues influence the quantitative evaluation process, such as ambient light conditions and device independence. Several approaches have been proposed to overcome the aforementioned challenges and to enhance the performance of smartphone-based colorimetric analysis. This chapter aims at providing researchers with a state-of-the-art overview of smartphone-based spectrometer and colorimetry, which includes hardware designs with 3D printers and sensors and software designs with image processing algorithms and smartphone applications. In addition, assay preparation to mimic the real-life testing environments and performance metrics for quantitative evaluation of proposed designs are presented with the list of new and future trends in this field

Optical Camera Communications: Principles, Modulations, Potential and Challenges

Optical wireless communications (OWC) are emerging as cost-effective and practical solutions to the congested radio frequency-based wireless technologies. As part of OWC, optical camera communications (OCC) have become very attractive, considering recent developments in cameras and the use of fitted cameras in smart devices. OCC together with visible light communications (VLC) is considered within the framework of the IEEE 802.15.7m standardization. OCCs based on both organic and inorganic light sources as well as cameras are being considered for low-rate transmissions and localization in indoor as well as outdoor short-range applications and within the framework of the IEEE 802.15.7m standardization together with VLC. This paper introduces the underlying principles of OCC and gives a comprehensive overview of this emerging technology with recent standardization activities in OCC. It also outlines the key technical issues such as mobility, coverage, interference, performance enhancement, etc. Future research directions and open issues are also presented

Development of Smartphone dual-laser waveguide based fluorescent microscopy system using 3D printing

Nowadays cellphones are present everywhere, and along with the worldwide network of devices, the concept of mobile health monitoring is changing to reshape the biosensor market. The smartphone’s camera is a proven reliable candidate as a detector for the studies performed by various research groups. This study is a proof of concept of the Smartphone detection of two fluorescent dyes which can be used as biomarkers for point-of-care diagnostics through image processing techniques. A smartphone Xiaomi Redmi Note 4 along with two fluorescent dyes DyLight™ 405 NHS Ester and DyLight™ 633 NHS Ester are used in conjunction with two lasers Thorlabs 405 nm and 638nm. The captured pictures were analyzed using Image J. The limit of detection and dynamic range values were calculated for both dyes, 28.39 nM and 20-800 nM for DyLight™ 405 NHS Ester dye and 15.85 nM and 10-600 nM for DyLight™ 633 NHS Ester dye. Then this concept is realized by developing a cheap 3D printed POC device which uses the optical microscopy technology along with a PDMS chip. Hence, this integrated novel innovation which prioritizes accuracy and the ease of usage, can be a game changer for patients who live in countries of limited resources and can moreover aid to the impoverished people who are in dire need of medical help

Detection and analysis of single event upsets in noisy digital imagers with small to medium pixels

Camera sensors are shrinking, resulting in more defects seen through image analysis. Due to cosmic radiation, camera experience both permanent defects known as hot pixels and temporal defective spikes which are Single Event Upsets (SEUs). SEUs manifest themselves as temporal random bright areas in sequential dark-frame images that are taken with long exposure times. In the past, it was difficult to separate SEUs from noise in dark-frame images taken with DSLRs at high sensitivity levels (ISO) and cell phone cameras at modest sensitivity levels. However, recent software improvements in this research have enabled the analysis of defect rates in noisy digital imagers – by leveraging local area and pixel address distribution techniques. In addition, multiple experiments were performed to understand the relationship of SEUs and elevation. This study reports data from imagers with pixels ranging from 7 μm (DSLR cameras) down to 1.2 μm (cell phone cameras)

Smartphone-based food diagnostic technologies: A review

A new generation of mobile sensing approaches offers significant advantages over traditional platforms in terms of test speed, control, low cost, ease-of-operation, and data management, and requires minimal equipment and user involvement. The marriage of novel sensing technologies with cellphones enables the development of powerful lab-on-smartphone platforms for many important applications including medical diagnosis, environmental monitoring, and food safety analysis. This paper reviews the recent advancements and developments in the field of smartphone-based food diagnostic technologies, with an emphasis on custom modules to enhance smartphone sensing capabilities. These devices typically comprise multiple components such as detectors, sample processors, disposable chips, batteries and software, which are integrated with a commercial smartphone. One of the most important aspects of developing these systems is the integration of these components onto a compact and lightweight platform that requires minimal power. To date, researchers have demonstrated several promising approaches employing various sensing techniques and device configurations. We aim to provide a systematic classification according to the detection strategy, providing a critical discussion of strengths and weaknesses. We have also extended the analysis to the food scanning devices that are increasingly populating the Internet of Things (IoT) market, demonstrating how this field is indeed promising, as the research outputs are quickly capitalized on new start-up companies

Visible Light Optical Camera Communication for Electroencephalography Applications

Due to the cable-free deployment and flexibility of wireless communications, the data transmission in the applications of home and healthcare has shown a trend of moving wired communications to wireless communications. One typical example is electroencephalography (EEG). Evolution in the radio frequency (RF) technology has made it is possible to transmit the EEG data without data cable bundles. However, presently, the RF-based wireless technology used in EEG suffers from electromagnetic interference and might also have adverse effects on the health of patient and other medical equipment used in hospitals or homes. This puts some limits in RF-based EEG solutions, which is particularly true in RF restricted zones like Intensive Care Units (ICUs). As a recently developed optical wireless communication (OWC) technology, visible light communication (VLC) using light-emitting diodes (LEDs) for both simultaneous illumination and data communication has shown its advantages of free from electromagnetic interference, potential huge unlicensed bandwidth and enhanced data privacy due to the line transmission of light. The most recent development of VLC is the optical camera communication (OCC), which is an extension of VLC IEEE standard 802.15.7, also referred to as visible light optical camera communication (VL-OCC). Different from the conventional VLC where traditional photodiodes are used to detect and receive the data, VL-OCC uses the imaging camera as the photodetector to receive the data in the form of visible light signals. The data rate requirement of EEG is dependent on the application; hence this thesis investigates a low cost, organic LED (OLED)-driven VL-OCC wireless data transmission system for EEG applications

Diagnostic Biosensors for Detection of Blood-Derived Biomarkers

Standard diagnostic tools used from patient samples, specifically from blood draws, require specialized equipment, personnel, and facilities. Conventional techniques can often be very laborious and time consuming due to required sample preparation. The evident delay from sample collection to a patient’s result immensely impacts their outcome. The aims of this research are to design diagnostic biosensors that decrease time-to-results, minimize reagent and sample handling, and incorporate automated simple optical transduction and user interfaces for the detection of blood-derived biomarkers. Specifically, four biosensing detection mechanisms performed on 3 different point-of-care platforms will be discussed. First is a static loop-mediated isothermal amplification (LAMP) of nucleic acid aqueous droplet on a silicone chip platform immersed in mineral oil. The target-of-interest is a nucleic acid sequence as a biomarker for antibiotic resistant bacteria. The biosensing technique used related changes in interfacial tension (IFT) at the water-oil interface by measuring the change in contact angle (geometrical-effects) over time. Initially the system was characterized as a linear response in relation to concentration of bacteria in a buffer system down to the limit of detection (LOD) of 100 CFU per uL. Subsequently, with the addition of bacterial infected blood sample models, the system became a binary assay (i.e. yes or no) as low as 10 CFU per uL within 10 min of reaction. Secondly, a two-layered, paper microfluidic chip was utilized to quantify cancer cells from a buffy coat sample matrix by two detection mechanisms: 1) on-chip particle enumeration via smartphone microscope and 2) capillary flow dynamics via smartphone video processing. The assay resulted in a LOD as low as 1 cell per uL for the on-chip imaging aspect of platform and 0.1 cell per uL for the capillary flow analysis within 13 to 22s post application of blood sample. Lastly, the same concepts previously described in the first platform utilizes changes in IFT due to amplicon presence in an aqueous solution immersed in mineral oil. An emulsion LAMP platform was investigated to determine the relation between angle-dependent light scatter intensity (based off Mie scatter theory) and nucleic acid amplification progression. The phenomenon attributing to changes in light scatter intensities is due to the interfacial changes occurring in the emulsion droplets, where amplicon amount increases the IFT decreases, resulting in smaller diameter emulsions. Changes in light scatter intensity within 3 min of the reaction shows statistical difference in comparison to no target control (NTC) for 10^3 CFU per uL of bacteria dosed into aqueous sample. These four detection mechanisms and three platforms offer but a few alternatives as biosensing methods for blood-derived diagnostic biosensors