Evaluating Calf Bioimpedance Measurements For Fluid Overload Management In A Controlled Environment

Objective: To evaluate the relationship between calf bioimpedance measurements and fluid removal in a controlled environment (hemodialysis) as a first step toward using these measurements for remote congestive heart failure (CHF) monitoring. Approach: Calf bioimpedance measurements were recorded in 17 patients undergoing hemodialysis (9/17 (53%) CHF, 5/17 (30%) female). Measurements were performed before and after hemodialysis. Additional parameters related to hemodialysis and patient fluid status such as estimated dry weight were also recorded. Main results: Calf bioimpedance changes depended on calf fluid status as assessed by calf normalized resistivity (CNR). Patients with lower calf fluid overload (as assessed by CNR greater than 0.1017 Ω m3 kg-1) had larger decreases in calf fluid than patients with higher calf fluid overload. High CNR patients had fluid changes within the calf that depended on the ultrafiltration rate, with patients with lower ultrafiltration rates experiencing fluid shifts from extracellular to intracellular fluid. Additionally, there were correlations between changes in calf extra-, intra- and total- water and the ultrafiltration volume removed for high CNR patients (R² = 0.44, 0.42, 0.56, respectively, all p-values \u3c 0.05). Significance: These results suggest that while the relationship between calf fluid status and total fluid status is complex, changes in calf volumes comparable to those expected in an ambulatory setting are measurable and relate to changes in total volume. This suggests that calf bioimpedance measurements for CHF remote monitoring warrant future investigation, as remote fluid status management could reduce fluid overload related hospitalizations in CHF patients

Electrocardiogram and Impedance Pneumography Measurement Module Design for Textile-Integrated Solution

A wearable electronics is a quickly broadening category in sport, wellbeing and entertainment products. Also a fully textile-integrated electronics is used increasingly to improve the user experience. The medical industry is interested to exploit especially the latter technology for a supported long-term home care. The problem is, there are only wellbeing promoting textile-integrated electronics at the moment. These products recommend for example how to prevent an injury, but do not provide the actual diagnostic value. Purpose of this master´s thesis was to increase knowledge of the biomedical instrumentation about diagnostics textile-integrated electronics – especially designed for long-term home monitoring of the elderly. For achieving this matter, into shirt integrated an electrocardiography (ECG) and impedance pneumography (IP) measurement module will be developed as a part of the Disappearing Sensors (DISSE) project. Preparation, like technical designing and functionality testing, have been made during this thesis for fulfilling described target. The functionality testing was implemented from three point of views: electrodes, measurement position, and measuring techniques for the ECG and IP. As electrodes were used commercial disposable electrodes, textile electrodes, and printed electrodes. Different measurement positions were laying, sitting, standing and walking slow and fast. As measurement techniques, 2- and 4-electrode measuring methods were compared by using commercial evaluation board. The work also considered a choose of the shirt and its final form in the prototype, which textile-integrated version will be completed during Autumn 2016. From electrodes the most stable results were gathered with disposal ones. However, the skin irritation caused by these electrodes is not suitable for a long-term monitoring. For the textile and printed electrodes skin irritation did not seem to be a problem. Random instabilities of the textile electrodes were reason why the printed electrodes were chosen to be the best alternative. Measuring positions, excluding walking, fulfilled the minimum goal to detect pulse and breathing. In walking tests heart and respiration rates can be detected, despite occasional errors, only with disposal electrodes. In order to achieve the this with printed electrodes, the skin-electrode-contact should be improved. From two measuring techniques the 4-electrode measuring method had worse signal quality, but pulse and breathing were detected with more accuracy compared to 2-electrode measuring method

Design and implementation of a multi-modal sensor with on-chip security

With the advancement of technology, wearable devices for fitness tracking, patient monitoring, diagnosis, and disease prevention are finding ways to be woven into modern world reality. CMOS sensors are known to be compact, with low power consumption, making them an inseparable part of wireless medical applications and Internet of Things (IoT). Digital/semi-digital output, by the translation of transmitting data into the frequency domain, takes advantages of both the analog and digital world. However, one of the most critical measures of communication, security, is ignored and not considered for fabrication of an integrated chip. With the advancement of Moore\u27s law and the possibility of having a higher number of transistors and more complex circuits, the feasibility of having on-chip security measures is drawing more attention. One of the fundamental means of secure communication is real-time encryption. Encryption/ciphering occurs when we encode a signal or data, and prevents unauthorized parties from reading or understanding this information. Encryption is the process of transmitting sensitive data securely and with privacy. This measure of security is essential since in biomedical devices, the attacker/hacker can endanger users of IoT or wearable sensors (e.g. attacks at implanted biosensors can cause fatal harm to the user). This work develops 1) A low power and compact multi-modal sensor that can measure temperature and impedance with a quasi-digital output and 2) a low power on-chip signal cipher for real-time data transfer