Robert Puers

In vivo forces on oral implants supporting a mandibular overdenture: the influence of attachment system.

Abstractu2002This study was designed to gain insight into the influence of the attachment system on the loading conditions of oral implants supporting a mandibular overdenture on two implants. Five patients were selected and were provided with two implants in the canine area of the mandible (Brånemark System). All patients received a new mandibular overdenture that could be mounted on an ovoid-shaped bar (Dolder, C&M): (a) with and (b) without bilateral extensions and (c) on ball-attachments (Nobel Biocare). Using three strain gauges attached to the outer surface of the 5.5-mm standard abutments, the axial forces and bending moments on both supporting implants could be quantified. Load registrations were made during application of 50 N on seven predetermined positions along the occlusal surface of the prosthesis and during maximal biting in maximal occlusion (clenching). The results revealed no differences in induced axial force for the various anchorage devices, unlike the differences in bending moment. Although there is a tendency for better axial load sharing with bars and better sharing of bending moments with ball attachments, these differences were not significant.

Mechanical characterization of poly-SiGe layers for CMOS?MEMS integrated application

Measuring mechanical properties at the microscale is essential to understand and to fabricate reliable MEMS. In this paper a tensile testing system and matching microscale test samples are presented. The test samples have a dog-bone-like structure. They are designed to mimic standard macro-tensile test samples. The micro-tensile tests are used to characterize 0.9 µm thick polycrystalline silicon germanium (poly-SiGe) films. The poly-SiGe film, that can be considered as a close equivalent to polycrystalline silicon (poly-Si), is studied as a very promising material for use in CMOS/MEMS integration in a single chip due to its low-temperature LPCVD deposition (T < 450 °C). The fabrication process of the poly-SiGe micro-tensile test structure is explained in detail: the design, the processing and post-processing, the testing and finally the results discussion. The poly-SiGe micro-tensile results are also compared with nanoindentation data obtained on the same poly-SiGe films as well as with results obtained by other research groups.

Electronic identification and monitoring of pigs during housing and transport

Abstract Ear base and rectal temperatures of 21 individually housed multiparous sows were measured in order to detect oestrus for optimal insemination time. A thermistor was implanted in the ear base and wire-connected to a data-acquisition system, allowing time-sampling with a measuring accuracy of 0.1°C. Air temperature in the neighbourhood of the sows was measured with the same equipment. Rectal temperature was measured each day in the afternoon with a veterinary thermometer. Following the rectal temperature measurement, a blood sample was taken to determine oestradiol-17 β-content. The combination of the physiological measurement with the observation of the standing reflex of the sows made oestrus detection very reliable. A statistically significant rise of ear base (1.1 ± 0.12°C) and rectal (0.65 ± 0.3°C) temperature was observed 2 days before oestrus. A total of 45 pigs were transported at a body weight of about 20 kg. At 1 week before transport a telemetric device was injected in the base of each pigs ear. Transmission of information was received by an aerial, which was integrated in the floor of the trailer, and was connected to a receiver with data management facilities. Accuracy and resolution of measuring body temperature was 0.1°C. During transport a statistically significant increase of ear base temperature (about 0.7°C) was observed. Data collection efficiency was estimated at 30%.

Micro-tensile tests to characterize MEMS

Measuring mechanical properties at the microscale is essential to understand and fabricate reliable MEMS. In this paper we present a tensile testing system and test samples on the microscale. The test samples have a dog-bone like structure. They were designed to mimic fundamental and standardized macro-tensile test samples. The micro-tensile tests were used to characterize 1.7mum thick AlCuMgMn films. This alloy was selected because it is a very promising material for use in RF-MEMS switches due to its high resistance to creep. We show that the mechanical properties of the AlCuMgMn film depend not only on the alloying components but also on the materials microstructure: grain sizes, distribution, strength and density of the precipitates, etc. We show a direct relation between the films mechanical properties and the coherence, size and spacing of precipitates as observed by SEM and TEM in the alloy.