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

An Optical Design Configuration for Wireless Data Transmission

The concept of 2D barcodes is of great relevance for use in wireless data transmission between handheld electronic devices. In a typical setup, any file on a cell phone for example can be transferred to a second cell phone through a series of images on the LCD which are then captured and decoded through the camera of the second cell phone. In this research, a new approach for data modulation in 2D barcodes is introduced, and its performance is evaluated in comparison to other standard methods of barcode modulation. In the proposed method, Orthogonal Frequency Division Multiplexing (OFDM) modulation is used together with Differential Phase Shift Keying (DPSK) over adjacent frequency domain elements to modulate intensity of individual pixels. It is shown that the bit error rate performance of the proposed system is superior to the current state of the art in various scenarios. A specific aim of this study is to establish a system that is proven tolerant to camera motion, picture blur and light leakage within neighboring pixels of an LCD. Furthermore, intensity modulation requires the input signal used to modulate a light source to be positive, which requires the addition of a dc bias. In the meantime, the high crest factor of OFDM requires a lower modulation index to limit clipping distortion. These two factors result in poor power efficiency in radio over fiber applications in which signal bandwidth is generally much less than the carrier frequency. In this study, it is shown that clipping a bipolar radio frequency signal at zero level, when it has a carrier frequency sufficiently higher than its bandwidth, results in negligible distortion in the pass band and most of the distortion power is concentrated in the baseband. Consequently, with less power provided to the optical carrier, higher power efficiencies and better receiver sensitivity will result. Finally, a more efficient optical integrated system is introduced to implement the proposed intensity modulation method which is optimized for radio over fiber applications

NASA Tech Briefs, June 1996

Topics: New Computer Hardware; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences;Books and Reports

Optical Coherence Tomography and Its Non-medical Applications

Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Portable colorimetric sensor array technology

Humans as a species are generally audio-visual creatures and do not take full advantage of the olfactory sense. Nonetheless, even humans can recognize and differentiate among thousands of different odorants under challenging conditions. Molecular recognition by the olfactory system derives its specifity from a complex pattern of responses generated by cross-reactive olfactory receptors. These receptors are encoded by approximately one thousand genes, which represents roughly 3% of the entire human genome. As a concept, the use of multiple cross-reactive chemical sensors is broadly applicable to any situation in which the sensors can be simultaneously exposed to each of a set of multiple target analytes; such an "artificial nose" has significant potential in all areas of chemical sensor technology. The chemical sensor arrays discussed in this work are based upon cross-reactive colorimetric response: each of many sensor elements in an array is a mixture of dyes or other compounds that changes color upon exposure to an analyte. These arrays typically use strong, poorly-reversible chemical reactions involving a diverse set of color-changing dyes or chromogens; such colorimetric sensor arrays have evolved to be fast, sensitive, portable, and inexpensive. Importantly, the analyte scope of the developed arrays has been shown to be capable of tailoring based on their intended applications, and can be made to be either broad or narrow as desired: in previous works, they have proven to be capable of discriminating among a broad range of analytes including both gaseous and aqueous analytes involving many different types of chemical reactivity, including Lewis and Brønsted acidity/basicity, molecular polarity, redox properties, and chelation. Of particular interest is the study of chemicals which are hazardous to human life, by either directly interacting with the human body or indirectly causing a physical effect. This work discusses development of colorimetric sensor arrays for two such cases: aqueous toxins and explosives materials. Both types of analytes are particularly challenging due to their relative lack of chemical reactivity: aqueous toxins derive their toxicity from interaction with specific proteins within the human body, while explosives have high potential energy but are kinetically inert. Targeting these analytes while still maintaining high sensitivity, low noise, and the ability to discriminate among them was the primary focus of these two projects. Further, inexpensive portable technology for the quantitative analysis of these arrays is vitally necessary for their intended use outside of the laboratory. This work discusses development of an automated, truly portable device that fits into a pocket and improves upon previous instrumentation in scan speed, sensitivity, and noise. Since colorimetric sensor arrays are monitored by optical transduction, development of portable scanners involves investigating inexpensive, compact, low-noise optical imagers. Previous works focused on flatbed scanners, which have since shown to have limitations in portability (flatbed scanners will certainly not fit in someone's pocket), scan speed (~15-45 seconds per scan), noise (largely induced by the scanner's moving parts), and processing ability (processed manually). To improve upon this, an optical line imager known as a contact image sensor was used to act as the optical transducer; chemical sensor arrays were printed linearly so as to maintain compatibility with the line imager. The final device included disposable sensor array cartridges, a flow control system, control software, and analysis software for pattern matching

Smart home technology for aging

The majority of the growing population, in the US and the rest of the world requires some degree of formal and or informal care either due to the loss of function or failing health as a result of aging and most of them suffer from chronic disorders. The cost and burden of caring for elders is steadily increasing. This thesis focuses on providing the analysis of the technologies with which a Smart Home is built to improve the quality of life of the elderly. A great deal of emphasis is given to the sensor technologies that are the back bone of these Smart Homes. In addition to the Analysis of these technologies a survey of commercial sensor products and products in research that are concerned with monitoring the health of the occupants of the Smart Home is presented. A brief analysis on the communication technologies which form the communication infrastructure for the Smart Home is also illustrated. Finally, System Architecture for the Smart Home is proposed describing the functionality and users of the system. The feasibility of the system is also discussed. A scenario measuring the blood glucose level of the occupant in a Smart Home is presented as to support the system architecture presented

NASA Tech Briefs, November 1990

Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

NASA Tech Briefs, September 2001

Topics include: special coverage section on sensors, and sections on electronic components systems, software, materials, machinery/automation, manufacturing/fabrication, bio-medical, book and reports, and a special section of Photonics Tech Briefs