Design and construction of small sized pencil probe to measure bio-impedance

Small-sized probe for local measuring electrical properties of the tissues inside of human body: design, modelling and simulation

In this study, a new idea is suggested for designing an appropriate bio-impedance probe in the form of a biopsy forceps to measure the electrical properties of the tissues inside the body. First, by analytically solving the Laplace equation for wedge-shaped tissue in the mouth of the probe, the relationship between electric potential (results from excitation current) in a different point on the tissue and the electrical properties of the tissue is obtained. Then, to evaluate the designed bio-impedance probe using the finite element method and the experimental data obtained for different tissues by Gabriel et al., modelling and simulation at different frequencies from 50 Hz to 5 MHz were done. Finally, to evaluate the performance of the designed probe in comparison to other methods, measurements were carried out using three methods for the same tissue. Nyquist curves were drawn and electrical properties extracted for all the three methods. It was found that the designed probe results are close to the actual values with an error of <2%. The main features of the designed probe are small size and non-invasive measurement.

Bladder cancer detection using electrical impedance technique (tabriz mark 1)

Bladder cancer is the fourth most common malignant neoplasm in men and the eighth in women. Bladder pathology is usually investigated visually by cystoscopy. In this technique, biopsies are obtained from the suspected area and then, after needed procedure, the diagnostic information can be taken. This is a relatively difficult procedure and is associated with discomfort for the patient and morbidity. Therefore, the electrical impedance spectroscopy (EIS), a minimally invasive screening technique, can be used to separate malignant areas from nonmalignant areas in the urinary bladder. The feasibility of adapting this technique to screen for bladder cancer and abnormalities during cystoscopy has been explored and compared with histopathological evaluation of urinary bladder lesions. Ex vivo studies were carried out in this study by using a total of 30 measured points from malignant and 100 measured points from non-malignant areas of patients bladders in terms of their biopsy reports matching to the electrical impedance measurements. In all measurements, the impedivity of malignant area of bladder tissue was significantly higher than the impedivity of non-malignant area this tissue (P < 0.005).

Some early results related to electrical impedance of normal and abnormal gastric tissue

Gastric cancer is the fourth most common cancer and most patients with gastric cancer are being diagnosed in advanced stages of the disease so they do not gain any survival chance from conventional surgical, chemotherapeutic or radiotherapeutic methods. These are relatively high cost procedures in terms of both time and money. This study considers the introduction of a novel minimally invasive diagnostic technique which shows the relationship between histopathology and the electrical impedance spectrum in the human stomach. In this study, 4 electrode technique was used to differentiate tissues from each other using Tabriz Mark 1 electrical impedance system (30 different frequencies in the range of 2 kHz to 1 MHz). A total of 97 points from 45 patients were studied in terms of their biopsy reports matching to the electrical impedance measurements (in vivo). After impedance measurements and applying calibration factors, a non-parametric statistical technique, the Kruskal-Wallis test was used to evaluate the difference among the groups. According to the calculation of respective data using this spectroscopy system, the resistivity of the normal group was higher than that of the benign group, and the resistivity of these groups were higher than that of the malignant group at frequencies between 470 kHz and 1 MHz (P < 0.05). In these frequencies, the impedivity of the dysplastic tissue was significantly lower than that of the other groups (P < 0.05). Also, Cole equation fitting procedure was used to generate a scatter plot of the malignant and benign points: it shows in general, benign points had higher values of R than the malignant points. Therefore, electrical impedance spectroscopy can be a useful technique to characterize the stomach tissue.

Surface fluids effects on the bladder tissue characterisation using electrical impedance spectroscopy

The electrical impedance of the human urinary bladder in both benign and malignant areas can be measured using an electrical impedance spectroscopy system (EIS). Glycine is usually used in the bladder surgery in the theatre to make an insulation medium for electro-surgery and the extension of the mucosa. In addition, a saline solution is usually used to wash the inside of the bladder after bladder surgery and it is used to extend the bladder tissue mucosa. Therefore, the effect of glycine and the saline solution that fills the bladder is important, because it was expected that the application of common surface fluids (air, saline solution and glycine solution) in the bladder epithelium would affect the measured electrical impedance of the urothelium, to differentiate the malignant area from the normal bladder tissue. In this study, bladders were removed from the patients' bodies and then were moved from theatre to the histopathology department immediately after excision. These bladder samples were then opened and pinned to a corkboard to take the impedance readings, using the impedance spectroscopy system. Following this, the bladder and corkboard were completely submerged in a saline solution and readings were taken at about 1cm from the sutures. Subsequently, this procedure was repeated with the bladder submerged in glycine and then air, respectively. According to the statistical work, these fluids were found to have a significant effect on the measured impedance of the bladder tissue in benign and malignant areas. Furthermore, the best fluid between air, glycine and saline, to measure the impedance of the urinary bladder, is air (P<0.0001).