Influence of fingerprints and finger positioning on accuracy of RF blood glucose measurement from fingertips

Non-invasive blood glucose measurement has attracted great interest from researchers deploying various techniques where microwave sensing is one of them. Microwave resonators are utilized as sensors for measuring the glucose levels. A body part is placed on the sensor for a reading and the measurement principle lies in the change of the dielectric properties of blood with varying levels of glucose. The fingertip is a popular measurement site as there is a good amount fresh blood supply. The position of the fingertip on the sensor has an effect on the sensor response due to the change in the propagation path of the electromagnetic field inside the finger. Moreover, fingerprints also affect the sensor response as the irregular ridges and valleys in the fingerprint introduce air gaps altering the effective permittivity seen by the sensor. The effects of fingerprints as well as finger positioning on the sensor is explored and explained in this paper

Simulating the Effects of Skin Thickness and Fingerprints to Highlight Problems with Non-invasive RF Blood Glucose Sensing from Fingertips

The non-invasive measurement of blood glucose is a popular research topic where RF/microwave sensing of glucose is one of the promising methods in this area. From the many available measurement sites in the human body, fingertips appear to be a good choice due to a good amount of fresh blood supply and homogeneity in terms of biological layers present. The non-invasive RF measurement of blood glucose relies on the detection of the change in the permittivity of the blood using a resonator as a sensor. However, the change in the permittivity of blood due to the variation in glucose content has a limited range resulting in a very small shift in the sensor’s frequency response. Any inconsistency between measurements may hinder the measurement results. These inconsistencies mostly arise from the varied thickness of the biological layers and variation of fingerprints that are unique to every human. Therefore, the effects of biological layers and fingerprints in fingertips were studied in detail and are reported in this paper

A Novel Pressure Sensing Circuit for Non-invasive RF/Microwave Blood Glucose Sensors

A novel pressure sensing circuit for non-invasive RF/microwave blood glucose sensors is presented in this paper. RF sensors are of interest to researchers for measuring blood glucose levels non-invasively. For the measurements, the finger is a popular site that has a good amount of blood supply. When a finger is placed on top of the RF sensor, the electromagnetic fields radiating from the sensor interact with the blood in the finger and the resulting sensor response depends on the permittivity of the blood. The varying glucose level in the blood results in a permittivity change causing a shift in the sensor’s response. Therefore, by observing the sensor’s frequency response it may be possible to predict the blood glucose level. However, there are two crucial points in taking and subsequently predicting the blood glucose level. These points are; the position of the finger on the sensor and the pressure applied onto the sensor. A variation in the glucose level causes a very small frequency shift. However, finger positioning and applying inconsistent pressure have more pronounced effect on the sensor response. For this reason, it may not be possible to take a correct reading if these effects are not considered carefully. Two novel pressure sensing circuits are proposed and presented in this paper to accurately monitor the pressure applied

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

Permittivity Extraction of Glucose Solutions Through Artificial Neural Networks and Non-invasive Microwave Glucose Sensing

An accurate low-cost method is presented for measuring the complex permittivity of glucose/water solutions. Moreover, a compact non-invasive RF/microwave sensor is presented for glucose sensing with the reasoning behind design parameters as well as simulation and measurement results. The complex permittivity values of aqueous solutions of glucose were measured with an in-house manufactured open-ended coaxial probe and the values were extracted from the measured complex reflection coefficients (S11) utilizing artificial neural networks. The obtained results were validated against a commercial probe. The values were fitted to the Debye relaxation model for ease of evaluation for a desired glucose concentration at a desired frequency. The proposed permittivity model in this paper is valid for glucose concentrations of up to 16 g/dl in the 0.3–15 GHz range. The model is useful for simulating and validating non-invasive RF glucose sensors

Energy harvesting from Microbial Fuel Cells – Wastewater to Electricity

MFCs have the potential to revolutionise wastewater treatment and catalyse a change in attitude towards wastewater as a commodity. It has been observed that domestic wastewater contains approximately 7.6 kJ/L of energy (Heidrich et al., 2011). In large-scale settings, wastewater could be used as an energy resource, offering huge savings in terms of cost and environmental burden. The major challenges facing the implementation of MFCs into wastewater treatment are scale up and energy harvesting/storage. In this study, a modular 20L air-breathing microbial fuel cell was developed alongside a smart energy harvesting (EH) system incorporating AI. The 20L air breathing MFC consists of modular cathode cassettes that enables easy maintenance and scale up to suit adaptive or changing end user requirements. PVDF/Stainless steel mesh cathodes are fabricated using phase inversion and oxygen reduction reaction catalysts incorporated in the polymeric matrix. Custom made carbon fibre brush electrodes are utilised as anodes. The system was inoculated with Shewanella Oneidensis MR-1 and ran under recirculating batch conditions. The MFC is monitored and controlled by a purpose-built circuit that tracks the performance of the individual cathode cassettes and configures the system via a custom Maximum Power Point Tracking (MPPT) algorithm for the best efficiency available for the given conditions. In addition, the circuit stores the extracted energy in a suitable energy storage element such as a capacitor bank or a rechargeable battery pack, with optimum charging levels. Moreover, the system is capable of learning multiple parameters associated with the MFC to optimise its parameters to maintain its high efficiency. The harvested energy can be used to power various types of electronic devices through the circuit's variable/adjustable power output. Heidrich, E., Curtis, T. and Dolfing, J. (2011). Determination of the Internal Chemical Energy of Wastewater. Environmental Science & Technology, 45 (2), 827-832. Available from 10.1021/es103058w

Health personnel perceptions about emergency contraception in primary health-care centers

WOS: 000186049000004PubMed ID: 14667325Objective The aim of this study was to assess the knowledge, attitudes and practices regarding emergency contraception in primary health-care workers. Methods This survey was conducted among health-care personnel in 20 primary healthcare centers in Izmir. A self-administered questionnaire was completed by 190 health-care personnel (doctors, nurses and midwives). Specific questions regarding knowledge of emergency contraception were asked. Results In all, 22% of personnel had received specialized training in family planning. Of the respondents, 53.7% had heard of emergency contraception. General practitioners were much more well informed than other health personnel. Conclusion Primary health-care personnel play a significant role in the provision of reproductive health care for women. There is a need to educate primary health-care personnel further about emergency contraception