A three-axis accelerometer for measuring heart wall motion

This thesis presents the work carried out in the design, simulation, fabrication and testing of miniaturised three-axis accelerometers. The work was carried out at the Faculty of Science and Engineering at Vestfold University College (Tønsberg, Norway), the MIcroSystems Engineering Centre (MISEC) at Heriot-Watt University and in collaboration with the Interventional Centre at Rikshospitalet University Hospital (Oslo, Norway). The accelerometers presented in this thesis were produced to be stitched to the surface of human hearts. In doing so they are used to measure the heart wall motion of patients that have just undergone heart bypass surgery. Results from studies carried out are presented and prove the concept of using such sensors for the detection of problems that can lead to the failure of heart bypasses. These studies were made possible using commercially available MEMS (MicroElectroMechanical Systems) three-axis accelerometers. However, the overall size of these sensors does not meet the requirements deemed necessary by the medical team (2(W) 2(H) 5(L) mm3) and fabrication activities were necessary to produce custom-made sensors. Design verification and performance modelling were carried out using Finite Element Analysis (FEA) and these results are presented alongside relevant analytical calculations. For fabrication, accelerometer designs were submitted to three foundry processes during the course of the work. The designs utilise the piezoresistive effect for the acceleration sensing and fabrication was carried out by bulk micromachining. Results of the characterisaton of the sensors are presente

Aquatic treadmill running reduces muscle soreness following intense sprint exercise in trained men

Delayed onset muscle soreness is associated with muscle damage, disturbances in proprioception, and decreases in muscular power. The purpose was to determine if short duration aquatic treadmill (ATM) running reduces muscle soreness following intense sprint exercise in trained men. Twenty trained men (180.3±4.4cm, 86.3±5.8kg, 20±1yr) were recruited and randomly divided into two groups: ATM recovery (ATMRec) and passive recovery (PRec). During testing, subjects performed a warm-up followed by sixteen 110yrd cutback runs with a sprint of 60yrds, sharp change of direction, and a return sprint of 50yrds. Work to rest ratio was set at 1:3. Additionally, following exercise, the ATMRec group performed ATM running using a HydroWorx® treadmill at 5mph, 50% maximal jet resistance, and water(33°C) level at chest depth for 10min. Both groups then evaluated their level of soreness/pain using a numerical rating scale (NRS: 0-10, 0=no pain, 10=worst pain) immediately following all exercise (IPE), 24h, and 48h post exercise in the following regions: ARMS, LEGS, BACK, CHEST, SHOULDERS, HIPS, ABDOMEN, NECK, OVERALL. Data were analyzed for group x time interactions using a 2x3 Generalized Linear Mixed Model for non-parametric data (α≤0.05). For significant interactions, the same procedure was used to analyze between group differences at the same measurement timepoint(α≤0.05)

Understanding anti-tuberculosis drug efficacy: rethinking bacterial populations and how we model them

Tuberculosis still remains a global health emergency, claiming 1.5 million lives in 2013. The bacterium responsible for this disease, Mycobacterium tuberculosis (M.tb), has successfully survived within hostile host environments, adapting to immune defence mechanisms, for centuries. This has resulted in a disease that is challenging to treat, requiring lengthy chemotherapy with multi-drug regimens. One explanation for this difficulty in eliminating M.tb bacilli in vivo is the disparate action of antimicrobials on heterogeneous populations of M.tb, where mycobacterial physiological state may influence drug efficacy. In order to develop improved drug combinations that effectively target diverse mycobacterial phenotypes, it is important to understand how such subpopulations of M.tb are formed during human infection. We review here the in vitro and in vivo systems used to model M.tb subpopulations that may persist during drug therapy, and offer aspirations for future research in this field

Exogenous proteinases in dairy technology

Glavna primjena proteinaza u mljekarskoj tehnologiji je u proizvodnji sira. Prikazana je prva enzimatska te druga ne-enzimatska faza koagulacije mlijeka sirilom. Ukratko su prodiskutirane mogućnosti zamjene telećeg sirila, a u detalje razvoj imobilizirajućih sirila. Razmatrana je također mogućnost ubrzanja zrenja sira dodavanjem proteinaza. Dat je pregled sporedne upotrebe proteinaza uključujući proizvodnju proteinskih hidrolizata, modifikaciju proteina i proizvodnju dječje hrane.The principal applications of proteinases in dairy technology are in cheese manufacture. The enzymatic primary phase and non-enzymatic secondary phase of rennet coagulation of milk are reviewed. Aspects of veal rennet substitutes are briefly discussed and developments in immobilized rennets considered in detail. The possibility of accelerating cheese ripening via added proteinases is also considered. Minor applications of proteinases including production of protein hidrolyzates, protein modification and baby food manufacture are reviewed

Design and fabrication of an implantable three-axis accelerometer for post-surgery monitoring of heart wall motion

The design and fabrication of mininiaturized three-axis accelerometers to be used in the measurement of heart wall motion are presented in this paper. Results from animal studies carried out by the group have already demonstrated the usefulness of large commercial accelerometers for this medical application. The advanced sensors proposed here consist of full wafer thickness masses supported by thin cantilever beams. Piezoresistors, which are implanted into the surface of the thin beams, are used to measure any acceleration that the masses undergo. ©2008 IEEE.</p