Ahmad Fairuz Omar

Turbidimeter Design and Analysis: A Review on Optical Fiber Sensors for the Measurement of Water Turbidity

Turbidimeters operate based on the optical phenomena that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within it. This review paper elaborates on the standards and factors that may influence the measurement of turbidity. The discussion also focuses on the optical fiber sensor technologies that have been applied within the lab and field environment and have been implemented in the measurement of water turbidity and concentration of particles. This paper also discusses and compares results from three different turbidimeter designs that use various optical components. Mohd Zubir and Bashah and Daraigan have introduced a design which has simple configurations. Omar and MatJafri, on the other hand, have established a new turbidimeter design that makes use of optical fiber cable as the light transferring medium. The application of fiber optic cable to the turbidimeter will present a flexible measurement technique, allowing measurements to be made online. Scattered light measurement through optical fiber cable requires a highly sensitive detector to interpret the scattered light signal. This has made the optical fiber system have higher sensitivity in measuring turbidity compared to the other two simple turbidimeters presented in this paper. Fiber optic sensors provide the potential for increased sensitivity over large concentration ranges. However, many challenges must be examined to develop sensors that can collect reliable turbidity measurements in situ.

Peak Response Identification through Near-Infrared Spectroscopy Analysis on Aqueous Sucrose, Glucose, and Fructose Solution

ABSTRACT The measurement of sugars is one of the important methodologies in determining fruits’ intrinsic quality, which can be collectively measured as soluble solids content (SSC) in the unit of oBrix. For fruits, oBrix is the summation of the grams of sucrose, glucose, fructose, vitamins, minerals, amino acids, proteins, hormones, and other soluble solids over 100 g of the particular fruit sample. Although lower range of near infrared (NIR) between 700 to 1100 nm is popularly being used in reliably determining soluble solids content of fruits, profiling of optical response of water-sugar concentration at this range of wavelength is not widely available. Thus, the purpose of this work is to optically profile water-sugar solutions and identify peak wavelengths in quantifying sugar concentration. Spectroscopic measurement in this work was conducted on the range of wavelength between 360 and 1100 nm. Wavelengths within 959–961 nm are identified as producing the highest coefficient of determination, R2, between absorbance and aqueous sugar concentration (oBrix). Combination of NIR wavelengths ( , 830, 909–915, 960, and 965 nm) within C-H and O-H bands can reliably quantify individual sugars, namely sucrose (calibration: R2 = 0.992, RMSEC = 0.907; prediction: R2 = 0.985, RMSEP = 1.221), glucose (calibration: R2 = 0.998, RMSEC = 0.426; prediction: R2 = 0.997, RMSEP = 0.540), and fructose (calibration: R2 = 0.996, RMSEC = 0.617; prediction: R2 = 0.995, RMSEP = 0.631).

NIR Spectroscopic Properties of Aqueous Acids Solutions

Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R2 above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918–925 nm and 990–996 nm, while at 975 nm for water.

Spectroscopic profiling of soluble solids content and acidity of intact grape, lime, and star fruit

Purpose – Visible and near infrared spectroscopy have been applied widely in fruits quality assessment especially on the measurement of soluble solids content (SSC) measured in oBrix and acidity measured in pH. Spectroscopy technique has been applied on three botanically different categories of fruits, that is: imported Californian table grape, Mandarin lime and star fruit. The purpose is to examine the ability of spectroscopy technique to quantify internal quality parameters with very narrow variability due to the characteristics of the raw material analyzed. This work also presents comparative study on peak wavelengths that can best be used to calibrate SSC and pH of different types of fruits.Design/methodology/approach – The effective wavelengths chosen for calibration development are compared with those selected by other researchers in similar experiments. NIR wavelengths 910 nm (C−H band) and 950 nm (O−H band) are the most important wavelengths for the prediction of SSC for all examined fruits while ...

Optical Sensor in the Measurement of Fruits Quality: A Review on an Innovative Approach

Agriculture industries are developing standards that evaluating on fruits intrinsic properties before it is put in the market for the consumer, unlike current standards that focuses only on the physical appearance of the fruits. To achieve this, there exist well established instruments to evaluate fruits intrinsic quality parameters such as firmness, acidity and sugar content. However, the current approach utilizes an invasive techniques and time consuming. Efforts have been delivered by various researchers world wide in making use of optical measurement techniques, specifically through spectrometer. While realizing that a specific biochemical composition is responsive the best at a certain wavelength, an effort is being made by researchers from University Science Malaysia in developing a specialize instrument in measuring fruits intrinsic quality. Besides, several works has also been accomplished in understanding optical phenomena in fruits to further enhance the current methodology in benefiting agriculture industry, especially farmers in producing only best quality of fruits to the market.

Visible spectroscopy calibration transfer model in determining pH of Sala mangoes

The purpose of this study is to compare the efficiency of calibration transfer procedures between three spectrometers involving two Ocean Optics Inc. spectrometers, namely, QE65000 and Jaz, and also, ASD FieldSpec 3 in measuring the pH of Sala mango by visible reflectance spectroscopy. This study evaluates the ability of these spectrometers in measuring the pH of Sala mango by applying similar calibration algorithms through direct calibration transfer. This visible reflectance spectroscopy technique defines a spectrometer as a master instrument and another spectrometer as a slave. The multiple linear regression (MLR) of calibration model generated using the QE65000 spectrometer is transferred to the Jaz spectrometer and vice versa for Set 1. The same technique is applied for Set 2 with QE65000 spectrometer is transferred to the FieldSpec3 spectrometer and vice versa. For Set 1, the result showed that the QE65000 spectrometer established a calibration model with higher accuracy than that of the Jaz spectrometer. In addition, the calibration model developed on Jaz spectrometer successfully predicted the pH of Sala mango, which was measured using QE65000 spectrometer, with a root means square error of prediction RMSEP = 0.092 pH and coefficients of determination R2 = 0.892. Moreover, the best prediction result is obtained for Set 2 when the calibration model developed on QE65000 spectrometer is successfully transferred to FieldSpec 3 with R2 = 0.839 and RMSEP = 0.16 pH.

Non-destructive quality evaluation of fruit by color based on RGB LEDs system

Fruits and vegetables are generally valued based on their visual appearance, particularly their color. Color is an important quality attribute that affects consumer acceptance and preference in the food industry. Human perception of color has been used as an indirect measure for classifying fruits in indices as fruits matured and ripened. This study was conducted to measure fruit quality by using visible optical fiber sensors that contains of RGB LEDs which are red, green and blue with peak wavelengths at 635 nm, 525 nm, and 470 nm, respectively. Moreover, this study aims to provide an innovative and low-cost approach for nondestructive fruit quality measurement. Multiple linear regressions was applied to develop calibration models for classifying fruits based on the index. Results showed that the proposed optical instruments can produce good and accurate measurements when evaluating the index. The highest coefficient of determination (R2 = 0.879), was obtained by using a combination of red, green, and blue data sets at various ripeness indices. Meanwhile, the optical fiber of red system generated by the monochromatic wavelength exhibited better precision (R2 = 0.795) compared with the other two wavelengths. In conclusion, the application of these systems leads to the rapid and efficient assessment of the quality measurement of mangoes.

Optical Fiber Near Infrared Spectroscopy for Skin Moisture Measurement

Skin covers the entire human body and function as shield from various types of external stimuli, damage and also from loss of moisture. The main characteristic factors for protecting the body and assisting in motion are the softness and pliability of skin (Obata and Tagami, 1990). These factors are dependent on the amount of moisture available in the stratum corneum, which is the outermost layer of skin. Modification in the amount of water content of the stratum corneum may lead to significant consequences to the functional properties of human skin. It is essential to retain sufficient moisture in the stratum corneum for healthy skin since the water level in this superficial layer of the human skin are of the utmost importance in determining many of its properties (Suh et al, 2005). Many instruments have been developed for studying skin physiology and among these applications, measurements of moisture in stratum corneum or sometimes also referred as hydration is one of the fundamental in the study of biophysical properties and function of the skin barrier (Fluhr et al, 1999). The most well-established technique to measure water content in skin is based on measuring electrical properties such as capacitance and alternating current conductivity on the skin surface (Arimoto et al, 2005). However, optical fiber near infrared spectroscopy technique has emerge as a popular substitute to conventional measuring methodology in various field of study including environmental monitoring, agricultural and food product quality analysis and also in medical, particularly skin health analysis. This mainly due to the technique which is seen to be able to produce measuring instruments that are non-destructive, portable, low cost, fast and easy operation besides having high precision and reproducibility. The integration of optical fiber probe into the spectroscopy system has added the flexibility of measurement and the fiber design itself can serve into raising the efficiency of measurement. For skin moisture measurement, one of the advantages of applying optical measuring technique is that the interface of optical fiber probe does not necessarily have to be made to contact the skin surface. Therefore, non-occlusive measurements can be made. To cater for the increasing interest in the development of optical fiber spectroscopy system, this chapter will present the existing application of upper range of NIR (11002500nm) and the possible application of lower range of NIR (700-1100nm) particularly 970nm in the measurement of skin moisture content.

Development of Optical Fiber Sensor for Water Quality Measurement

The development of water quality fiber sensor through spectroscopy analysis utilizes the emission of incident light and detection of backscattered light through fiber optic cables as key elements of the design. The system has the capability to detect the light scattered 180° away from the incident light when there is an interaction between the light and the solids suspended in the water. The empirical analysis is conducted for the measurement of the capacity of clay suspended in water (in mg/L). The system consists of two separate light detector circuitry that is sensitive to blue (470 nm) and red (635 nm) monochromatic light. The heart of the system is the sensor, TSLB257 and TSLR257 that having a peak response at wavelength of 470 nm and 635 nm respectively. The final result of detection is submitted to Basic Stamp 2 microcontroller for processing and analysis. The level of turbidity is then defined and displayed by the microcontroller.

Simplified optical fiber RGB system in evaluating intrinsic quality of Sala mango

Abstract. This study presents an alternative approach for the nondestructive assessment of fruit quality parameters with the use of a simplified optical fiber red–green–blue system (OF-RGB). The optical sensor system presented in this work is designed to rapidly measure the firmness, acidity, and soluble solid content of an intact Sala mango on the basis of color properties. The system consists of three light-emitting diodes with peak emission at 635 (red), 525 (green), and 470 nm (blue), as well as a single photodetector capable of sensing visible light. The measurements were conducted using the reflectance technique. The analyses were conducted by comparing the results obtained through the proposed system with those measured using two commercial spectrometers, namely, QE65000 and FieldSpec 3. The developed RGB system showed satisfactory accuracy in the measurement of acidity (R2=0.795) and firmness (R2=0.761), but a relatively lower accuracy in the measurement of soluble solid content (R2=0.593) of intact mangoes. The results obtained through OF-RGB are comparable with those measured by QE65000 and FieldSpec 3. This system is a promising new technology with rapid response, easy operation, and low cost with potential applications in the nondestructive assessment of quality attributes.