All-Digital 1550 nm Optical Aqueous Glucose Solution Measurement System

An all-digital 1550 nm optical measurement system is proposed for measuring the concentration of aqueous solutions of glucose to investigate the feasibility of NIR blood glucose measurements. A microcontroller was used to generate the excitation signal for a 1550 nm laser module as well as generate the reference signal to perform the lock-in amplifier function. A sine wave was generated inside the firmware to drive the laser module through a current DAC. The reference signal was generated by reading the monitor diode inside the laser module through the microcontroller’s internal ADC. A cooled photodetector was used to measure the light level where its output was digitized by a 24-bit ADC after analog signal conditioning. The glucose concentration result for the measurement was calculated performing DSP functions using the mentioned signals as set out in this paper. A correlation was successfully observed between measured signal level and glucose concentration

Ultrasensitive Tapered Optical Fiber Refractive Index

Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate highly sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5-45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due to the interaction of the propagating light in the evanescent field with glucose molecules. The coating of the TOF with gold nanoparticles (AuNPs) as an active layer for glucose sensing generated LSPR through the interaction of the evanescent wave with AuNPs deposited at the tapered waist. The results indicated that the TOF (Ø = 5 µm) exhibited improved sensing performance with a sensitivity of 1265%/RIU compared to the TOF (Ø = 12 µm) at 560%/RIU towards glucose. The AuNPs were characterized using scanning electron microscopy and ultraviolent-visible spectroscopy. The AuNPs-decorated TOF (Ø = 12 µm) demonstrated a high sensitivity of 2032%/RIU toward glucose. The AuNPs-decorated TOF sensor showed a sensitivity enhancement of nearly 4 times over TOF (Ø = 12 µm) with RI ranging from 1.328 to 1.393. The fabricated TOF enabled ultrasensitive glucose detection with good stability and fast response that may lead to next-generation ultrasensitive biosensors for real-world applications, such as disease diagnosis

Efficiency of evanescent excitation and collection of spontaneous Raman scattering near high index contrast channel waveguides

info:eu-repo/semantics/publishe

Nanoscale Heat Transfer from Magnetic Nanoparticles and Ferritin in an Alternating Magnetic Field

Recent suggestions of nanoscale heat confinement on the surface of synthetic and biogenic magnetic nanoparticles during heating by radio frequency-alternating magnetic fields have generated intense interest because of the potential utility of this phenomenon for noninvasive control of biomolecular and cellular function. However, such confinement would represent a significant departure from the classical heat transfer theory. Here, we report an experimental investigation of nanoscale heat confinement on the surface of several types of iron oxide nanoparticles commonly used in biological research, using an all-optical method devoid of the potential artifacts present in previous studies. By simultaneously measuring the fluorescence of distinct thermochromic dyes attached to the particle surface or dissolved in the surrounding fluid during radio frequency magnetic stimulation, we found no measurable difference between the nanoparticle surface temperature and that of the surrounding fluid for three distinct nanoparticle types. Furthermore, the metalloprotein ferritin produced no temperature increase on the protein surface nor in the surrounding fluid. Experiments mimicking the designs of previous studies revealed potential sources of the artifacts. These findings inform the use of magnetic nanoparticle hyperthermia in engineered cellular and molecular systems

Comparative Study of Different Near-Infrared (NIR) Wavelengths on Glucose Concentration Detection

There are a lot of in-vitro non-invasive techniques to measure a glucose concentration and one of them is by using near-infrared (NIR) spectroscopy. In this study, the main objective is to compare the behaviour on the different wavelengths of NIR transmitter (1050 nm, 1200 nm, 1300 nm, 1450 nm, and 1550 nm) on different glucose concentration solutions (0 to 300 mg/dL) and the measurement indicates a correlation between voltage and glucose concentration. The conditional circuit of NIR transmitter and detector is designed in order for the transmitter to transmit an optimal intensity of light. Besides, it also consists of the filter and amplifier used to filter and amplify the signal from the noise on the detector side. The transmitter and detector are positioned facing each other and the cuvette that filled with glucose solution is located in between. A placeholder casing for the experimental setup is designed to reduce an external error during the data collection. The voltage outputs are recorded for every different glucose concentrations by using different transmitter wavelength. Based on the results, it shows that the voltage output reading is directly proportionate to the glucose concentrations. These behaviours are similar to all different transmitter wavelengths used. The R-square (R2) and root-mean-square error (RMSE) for every wavelength used are varied. The result of using 1450 nm wavelength shows the best correlation between voltage outputs and glucose concentrations compared to other wavelengths with the highest value of R2. A linear equation is extracted from the fitted graph and can be used to predict the value of glucose concentrations

Ultrasensitive Tapered Optical Fiber Refractive Index Glucose Sensor

Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate extremely sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5–45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due to the interaction of the propagating light in the evanescent field with glucose. The coating of the TOF with gold nanoparticles (AuNPs) as an active layer for glucose sensing generated LSPR through the interaction of the evanescent wave with AuNPs deposited at the tapered waist. The results indicated that the TOF (Ø = 5 µm) exhibited improved sensing performance with a sensitivity of 1265%/RIU compared to the TOF (Ø = 12 µm) at 560%/RIU towards glucose. The AuNPs were characterized using scanning electron microscopy and ultraviolent-visible spectroscopy. The AuNPs-decorated TOF (Ø = 12 µm) demonstrated a high sensitivity of 2032%/RIU toward glucose. The AuNPs- decorated TOF sensor showed a sensitivity enhancement of four times over TOF (Ø = 12 µm) with RI ranging from 1.328 to 1.393. The fabricated TOF enabled ultrasensitive glucose detection with good stability and fast response that may lead to next-generation ultrasensitive biosensors for real-world applications, such as disease diagnosis

Effects of noises on near infrared sensor for blood glucose level measurement

This paper proposed the method of measuring glucose level in solution using near infrared light (NIR) and photodiode sensor. We studied noises that occurred on the output signal of NIR sensor in three different room conditions in order to know the effects on this sensor output voltage stability. The sensor’s circuit consisted of a 1450 nm NIR light emitting diode, a photodiode as the receiver, transimpedance amplifier, a notch filter, and a 4th order low pass filter. The results indicated that sunlight passing through windows was the most influencing factor caused the unstable sensor output voltage. Filters removed the effective voltages and the average sensor output voltages from the three rooms were 4.6825 V for air media, 2.2809 V for water media and 2.3368 V for glucose solution media. The output voltages tended to increase for one-hour measurement about 10 to 40 mV for air media, 40 to 90 mV for water media and 30 to 80 mV for glucose solution media. This sensor could only be used in a short time and suitable in a room without sunlight. Based on the voltage difference of the average sensor output voltage with water and glucose solution media, the sensor had the potential to be a blood glucose level meter