Electrical characteristics of female and male human skin

Bioimpedance spectroscopy (BIS) is a popular method for characterizing the electrical properties of biological tissues. In this study, BIS measurement data of female and male human skin were analyzed and compared. The electrical characteristics of tissue were followed according to four-parameters of the Cole-Cole model: low frequency resistance R0; high frequency resistance R∞; relaxation time t and parameter a. Individual electrical characteristics of human skin were determined for 30 women and 30 men. The distribution and one-way analysis of variance (one-way ANOVA) of the Cole-Cole parameters R0, R∞, t, a within the human population indicated their different dependence on gender. Parameter a, which is higher in the female subjects (a =0.83±0.03) than in the male subjects (a=0.7±0.05), is strongly dependent on gender (p=0). Parameter R∞ also significantly depends on gender (p=0.002), while t and R0 seem to be slightly related to gender (p>0.05). [Acknowledgments - This work was supported by the Ministry of Education and Science of the Republic of Serbia (41006).

A Feasibility Study of the Suitability of an AD5933-based Spectrometer for EBI Applications

Projecte final de carrera realitzat en col.laboració amb University of BoräsElectrical Bioimpedance (EBI) measurements have proven their validity in several medical applications like body composition analysis and detection of melanoma among others. The successful application of EBI technology on the field of medicine has lead the way for applications in the field of personal healthcare and body performance in the field of sports. Due to the widespread use of the EBI technology and rising of new EBI applications requiring system portability or even suitable to wear, the manufacturer Analog devices has introduced in the market the first integrated system dedicated to measure EBI, the impedance network analyzer AD5933. The availability of this EBI spectrometer device opens up new horizons for the integration of the measurement systems to meet the demands of new EBI applications and allowing the development of portable and even wearable measurement systems. This project is focused on the AD5933 impedance network analyzer, and it aims to identify the EBI applications in which, the use of an AD5933 device is suitable. To adapt the AD5933 device for biomedical measurements an Analog Front-End (AFE) has been used to enable the system for 4-electrodes measurements. In order to evaluate the performance of AD5933 with the AFE, experimental measurements on electrical equivalent models have been taken with the AD5933+4E-AFE system and the EBI spectrometer Impedimed SFB7. The obtained impedance spectral data have been used to estimate the values of the equivalent circuit under measurement and the estimated values have been mutually compared in terms of estimation accuracy

Electrical characteristics of female and male human skin

Bioimpedance spectroscopy (BIS) is a popular method for characterizing the electrical properties of biological tissues. In this study, BIS measurement data of female and male human skin were analyzed and compared. The electrical characteristics of tissue were followed according to four-parameters of the Cole-Cole model: low frequency resistance R0; high frequency resistance R∞; relaxation time t and parameter a. Individual electrical characteristics of human skin were determined for 30 women and 30 men. The distribution and one-way analysis of variance (one-way ANOVA) of the Cole-Cole parameters R0, R∞, t, a within the human population indicated their different dependence on gender. Parameter a, which is higher in the female subjects (a =0.83±0.03) than in the male subjects (a=0.7±0.05), is strongly dependent on gender (p=0). Parameter R∞ also significantly depends on gender (p=0.002), while t and R0 seem to be slightly related to gender (p>0.05)

Assessment of Volume Status in Peritoneal Dialysis Patients

Ideal volume status of patients with end-stage renal disease is one of the main goals of adequate dialysis. Volume overload has been associated with heart failure, left ventricular hypertrophy, and mortality, both in hemodialysis (HD) and peritoneal dialysis (PD) populations. The assessment of normal volume status is traditionally based on clinical parameters such as blood pressure, edema, lung auscultation, and chest X-ray. However, these parameters cannot be trustworthy to direct treatment decisions. Gold standard methods of assessing volume status are mainly isotope dilution analysis techniques. However, these methods are invasive and impractical in clinical routine. A number of handy bedside methods have been developed focusing on objective fluid status assessment, both in HD and PD patients. Bioimpedance techniques can estimate extracellular volume, intracellular volume, and total body water, whereas inferior vena cava diameter measurements, biochemical markers, and lung ultrasound provide information about the intravascular filling state and blood volume. Various studies have used the values of the above-mentioned techniques as tools for determining the overhydration of dialysis patients as well as predictors of mortality. Yet, randomized intervention studies based on these methods with hard end points (like echocardiographic parameters modification) have not been published so far in PD patients

A Galvanic Coupling Method for Assessing Hydration Rates

Recent advances in biomedical sensors, data acquisition techniques, microelectronics and wireless communication systems opened up the use of wearable technology for ehealth monitoring. We introduce a galvanic coupled intrabody communication for monitoring human body hydration. Studies in hydration provide the information necessary for understanding the desired fluid levels for optimal performance of the body’s physiological and metabolic processes during exercise and activities of daily living. Current measurement techniques are mostly suitable for laboratory purposes due to their complexity and technical requirements. Less technical methods such as urine color observation and skin turgor testing are subjective and cannot be integrated into a wearable device. Bioelectrical impedance methods are popular but mostly used for estimating total body water with limited accuracy and sensitive to 800 mL–1000 mL change in body fluid levels. We introduce a non-intrusive and simple method of tracking hydration rates that can detect up to 1.30 dB reduction in attenuation when as little as 100 mL of water is consumed. Our results show that galvanic coupled intrabody signal propagation can provide qualitative hydration and dehydration rates in line with changes in an individual’s urine specific gravity and body mass. The real-time changes in galvanic coupled intrabody signal attenuation can be integrated into wearable electronic devices to evaluate body fluid levels on a particular area of interest and can aid diagnosis and treatment of fluid disorders such as lymphoedema

Management of Fluid Status in Haemodialysis Patients: The Roles of Technology and Dietary Advice, Technical Problems in Patients on Hemodialysis

The kidneys play a vital role in maintaining normal tissue hydration and serum sodium level. In haemodialysis patients, with impaired or absent kidney function, fluid status is managed by removing excess fluid using ultrafiltration and by restricting dietary sodium intake. Ideally, haemodialysis patients should remain close to normal hydration throughout the interdialytic period, with minimal periods of excessive dehydration or fluid overload and with no fluid–related co-morbidity. Optimal fluid management is achieved by adjusting the post-dialysis ‘target’ weight and, where necessary, limiting the fluid gained between dialysis sessions. While clinical history and examination remain the basis for prescribing the target weight, technology can provide useful objective information especially where the clinical indications are ambiguous. A simple non-invasive test can now be carried out when a patient attends for dialysis enabling staff to pick up changes in body composition so that their target weight can be adjusted to maintain optimal fluid status. In most patients, interdialytic fluid gain (IDFG) is directly related to sodium intake. Acceptable fluid gains can usually be achieved by limiting salt intake to the recommended daily allowance for the general population and avoiding unnecessary sodium loading during dialysis. Low pre-dialysis serum sodium levels can help identify patients with other causes of high IDFG, such as high blood sugar or social drinking, who need additional counselling. For the patients, lowering sodium intake may also improve blood pressure control and reduce requirements for antihypertensive medication. Staff education, and preferably participation, is vital when implementing salt restriction in a haemodialysis unit

Lipid droplet detection by the cavity perturbation method

There are currently no point-of-care diagnosis strategies available to indicate the presence of neoplasmic growth. This research aims to develop a novel diagnostic strategy based on detecting TAG accumulation in cells. This element of the research is a preliminary experiment to prove the concept of detecting TAG lipid droplets in YEPD media. It was found that a change in mono-unsaturated concentration can be detected by the frequency shift in a resonant cavity. The dielectric constant of TAG vegetable oils was calculated at 2.34-2.39. It was also found that concentrations of lipid droplet can be differentiated up to 5% (v/v)