Thermal dosimetry for bladder hyperthermia treatment. An overview.

The urinary bladder is a fluid-filled organ. This makes, on the one hand, the internal surface of the bladder wall relatively easy to heat and ensures in most cases a relatively homogeneous temperature distribution; on the other hand the variable volume, organ motion, and moving fluid cause artefacts for most non-invasive thermometry methods, and require additional efforts in planning accurate thermal treatment of bladder cancer. We give an overview of the thermometry methods currently used and investigated for hyperthermia treatments of bladder cancer, and discuss their advantages and disadvantages within the context of the specific disease (muscle-invasive or non-muscle-invasive bladder cancer) and the heating technique used. The role of treatment simulation to determine the thermal dose delivered is also discussed. Generally speaking, invasive measurement methods are more accurate than non-invasive methods, but provide more limited spatial information; therefore, a combination of both is desirable, preferably supplemented by simulations. Current efforts at research and clinical centres continue to improve non-invasive thermometry methods and the reliability of treatment planning and control software. Due to the challenges in measuring temperature across the non-stationary bladder wall and surrounding tissues, more research is needed to increase our knowledge about the penetration depth and typical heating pattern of the various hyperthermia devices, in order to further improve treatments. The ability to better determine the delivered thermal dose will enable clinicians to investigate the optimal treatment parameters, and consequentially, to give better controlled, thus even more reliable and effective, thermal treatments

Electrochemical microsensors for cutaneous surface analysis: Application to the determination of pH and the antioxidant properties of stratum corneum

Potentiometry and cyclic voltammetry were proposed as simple, reliable and non invasive methods for the simultaneous determination of pH and antioxidant properties of skin. Experiments were performed with microelectrodes just deposited on skin surface without any gel or water added. pH was measured by means of the zero current potential of a tungsten W/WO3 sensor. A nerstian response was recorded in pH range 4 to 6 corresponding to the normal skin pH values. The global antioxidant capacity was deduced from the anodic charge passed during the plotting of cyclic voltammograms on platinum or gold microelectrodes. Comparing the half wave or peak potentials of these curves with those recorded for experiments performed in aqueous solution, the main hydrophilic antioxidants species were detected, i.e. ascorbic acid, uric acid and glutathione. This relatively easy-to-use analytical method made it possible to follow in real time the efficiency of topic treatment as well as to study the influence of oxidative stres

Instrument- Mounted Pressure-Sensing System For Surgical Applications

M.S. Thesis. University of Hawaiʻi at Mānoa 2017

Textile sensors to measure sweat pH and sweat-rate during exercise

Sweat analysis can provide a valuable insight into a person’s well-being. Here we present wearable textile-based sensors that can provide real-time information regarding sweat activity. A pH sensitive dye incorporated into a fabric fluidic system is used to determine sweat pH. To detect the onset of sweat activity a sweat rate sensor is incorporated into a textile substrate. The sensors are integrated into a waistband and controlled by a central unit with wireless connectivity. The use of such sensors for sweat analysis may provide valuable physiological information for applications in sports performance and also in healthcare

Development of a Cellulose Acetate Multisensorial Membrane

Biological fluids are the most measured media to monitor metabolites like glucose. Glucose measuring is important since it requires routine track for pa-tients undergoing self-testing, like patients diagnosed with pathologies that re-quire daily control of these metabolites or people who have problems with blood collection like haemophiliacs. It can prove to be painful and stressful collecting samples since most methods are invasive. The well-being and life quality of these patients can be improved by per-forming non-invasive tests to body fluids at the surface of the skin without ever losing biochemical profiling. Sweat and saliva can be collected more frequently this way, proving less painful and less stressful to the patients. By combining different biosensing functionalities in a unique membrane, in order to make it multisensorial, and integrate it in a wearable device which can be used on the skin’s surface as a band-aid, it’s possible to perform auto diagnosis keeping in mind a reduced cost policy, portability and ecology. In this work, cellulose acetate membranes, produced by electrospinning, were used in the construction of electrochemical devices and these were tested for pH and different concentrations of glucose

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

Compact Antenna with Artificial Magnetic Conductor for Noninvasive Continuous Blood Glucose Monitoring

A non-invasive technique for real-time continuous monitoring of blood glucose has been under development by Venkataraman’s research group in the ETA lab at RIT [16]-[18]. The methodology involves placing an antenna on the arm and monitoring changes in the resonant frequency, which is attributed to changes in the blood glucose level. This is because the blood’s permittivity depends on the glucose levels, and in turn, affects the antenna’s resonant frequency. In order to correlate the antenna’s resonant frequency shift with the real-time blood glucose change, glucose estimation was also modeled using the antenna’s input impedance. The antennas designed could successfully track the rise and fall of blood glucose using the glucose estimation model for both diabetic and non-diabetic patients. However, the antennas being used in this research are too large in size and not flexible. Additionally, the antenna’s radiation pattern was omnidirectional as it is a monopole antenna where the radiation is into the arm as well as away from the arm (back radiation). As a result, during the test procedure, the arm must be in a steady position throughout the time of the resonant frequency measurement. While it worked very well to prove the feasibility of continuous glucose monitoring, a better antenna is required for the next phase of research that involves clinical testing in a hospital environment. My goal in this thesis is to take the research further by designing antennas that are unidirectional, flexible and small in size. The unidirectional property can be achieved by using PEC (Perfect Electric Conductors) or PMC (Perfect Magnetic Conductors) over the antenna that can suppress the back radiation. Unlike the presence of infinite electric charges on an electric conductor, magnetic charges don’t exist. Therefore magnetic conductors are modeled artificially to achieve magnetic properties commonly known as Artificial Magnetic Conductors (AMC). The antenna used in this thesis is a monopole antenna with AMC as a ground plane. The advantage of using AMC over a perfect metal conductor as a ground plane to the antenna is that the AMC reflects the incident wave in phase and not out of phase like a regular metal conductor. Moreover, AMC layers not only suppresses the back radiation but also enhances the gain of the antenna into the arm. Using the AMC layer as the ground plane has also helped in miniaturizing the antenna. The different artificial magnetic conductors designed in this thesis are Rectangular Patch, Rectangular Ring, I-shaped, and Jerusalem Cross. The antennas were fabricated and tested in the unlicensed ISM band (2.4GHz – 2.5GHz) and are within the SAR standards laid out by FCC. The fabricated antenna was strapped to the arm and measurements of resonant frequency similar to those made previously were conducted with respect to time [16]-[18]. Two types of measurements were compared, that is, when the arm was held steady and when the arm had some movement. No significant change or fluctuations in the resonant frequency was observed with arm movement. Whereas the same type of measurements conducted on the monopole antenna in [18] showed significant fluctuations in the resonant frequency with arm movement. This experiment shows the significant advantage of the antenna with AMC layer as compared to the monopole antenna. Also demonstrated in the present work, is the ability of the designed antenna in tracking the increase and decrease of glucose level with changes in the resonant frequency, similar to [16]. This has been demonstrated with two non-diabetic subjects. Further, no back radiation was noted, when a hand above the setup is moved. Additionally, the effect of creeping waves was negligible. The antenna designed in this work will conform well to clinical studies of the ETA Lab research

Microfabricated tactile sensors for biomedical applications: a review

During the last decades, tactile sensors based on different sensing principles have been developed due to the growing interest in robotics and, mainly, in medical applications. Several technological solutions have been employed to design tactile sensors; in particular, solutions based on microfabrication present several attractive features. Microfabrication technologies allow for developing miniaturized sensors with good performance in terms of metrological properties (e.g., accuracy, sensitivity, low power consumption, and frequency response). Small size and good metrological properties heighten the potential role of tactile sensors in medicine, making them especially attractive to be integrated in smart interfaces and microsurgical tools. This paper provides an overview of microfabricated tactile sensors, focusing on the mean principles of sensing, i.e., piezoresistive, piezoelectric and capacitive sensors. These sensors are employed for measuring contact properties, in particular force and pressure, in three main medical fields, i.e., prosthetics and artificial skin, minimal access surgery and smart interfaces for biomechanical analysis. The working principles and the metrological properties of the most promising tactile, microfabricated sensors are analyzed, together with their application in medicine. Finally, the new emerging technologies in these fields are briefly described

New insight in biomedical measurements

L'abstract è presente nell'allegato / the abstract is in the attachmen