Sensitive Strain Gauge Research Articles

The CSIRO Hopkinson Bar Facility for large diameter particle breakage

The new CSIRO Hopkinson Bar Facility has been commissioned at the Queensland Centre for Advanced Technologies in Brisbane, Australia. Similar devices, such as the Ultra Fast Load Cell (UFLC) at the Utah Comminution Centre have proven to be extremely useful in providing fundamental breakage data of particulate material. In addition to its 19 mm and 60 mm diameter Hopkinson bars, the new CSIRO facility includes a large 100 mm Hopkinson Bar. This large diameter carbon steel load cell is instrumented with highly sensitive semi-conductor strain gauges that give it a force resolution of less than 100 Newtons, permitting precise measurement of the energy to fracture large mineral particles. The device's ability to measure breakage properties, such as first fracture force and energy, of large particles up 100 mm is unique. Breakage data for iron ores over a wide size range is presented. The well known comminution result of increasing particle strength and fracture energy with decreasing particle size was confirmed for the iron ores tested. The influence of iron ore mineralogy and texture was also noted.

Sensitive Strain Gauge Using a CMOS IC Combined with an Amorphous Magnetostrictive Wire Cantilever Beam

A highly sensitive linear strain gauge using a pair of amorphous CoSiB wires fixed to a plastic cantilever beam combined with a CMOS IC multivibrator circuit is presented. The wires are magnetized with a sharp pulse current to generate the stress impedance (SI) effect, showing a gauge factor of about 2000 in the CMOS IC circuit The linear strain gauge shows a resolution of about 2.5 mg for weight detection with high linearity in the range of −0.75∼1.25 g. The mechanism of the SI characteristics in the CoSiB wire is analyzed using a magnetization rotation model. Pulsation of fingertip blood vessels was stably detected by using the SI gauge stress sensor.

Capillary filtration coefficient in type II (non-insulin-dependent) diabetes

Changes in microvascular permeability may be important in the pathogenesis of diabetic microangiopathy. In order to assess microvascular fluid permeability, the capillary filtration coefficient was determined in the forearm of 24 normotensive type II diabetic patients with minimal evidence of microangiopathy and satisfactory glycemic control, and 24 age- and sex-matched control subjects, using a sensitive strain gauge plethysmographic system. The median capillary filtration coefficient was not significantly different in the type II diabetic patients and control subjects [5.3 (3.2 – 9.1) × 10 −3 mL·min −1·100 g tissue −1·mm Hg −1 versus 5.4 (3.5 – 8.0) × 10 −3 mL·min −1·100 g tissue −1·mm Hg −1, p = 0.98)]. There were no correlations between capillary filtration coefficient and age, blood pressue, body mass index, duration of diabetes, glycemic control, or the presence of microvascular complications. These findings contrast with type I diabetes, where capillary filtration coefficient is elevated at an early stage in the disease, and lend support to the theory that there are differences in early microvascular functional abnormalities between type I and type II diabetes.

特集 火山活動と地殻応力場 地殻歪の指示者としての火山噴火

Time-space relation between major eruptions in Izu region and large earthquakes along the Sagami Trough shows the following correlation : T= 49.88-21.04 logD, where T is the time interval from beginning of a major eruption to the occurrence of the large earthquake in year and D is the distance in km from the epicenter to the volcano. The relationship reveals that the time interval is shorter as the distance between the epicenter and the volcano is smaller. This suggests that a future shock area gives a stress increase to the volcano and a major eruption occurs by squeezing up of magma. Then, it would be followed by a large earthquake along the Sagami Trough to release a compressional strain accumulation. Subsequently, the magma reservoir is expanded and the magma head subsides down, and a series of the volcanic activities ceases. This change is closely related to a level change of the magma head in the summit crater of Izu-Oshima Volcano. Thereby, Izu-Oshima Volcano has a role as a very sensitive strain gauge. The time-space relationship suggests that the strain in the region along the middle Sagami Trough has been accumulated since the major eruption of Izu-Oshima Volcano in 1986.

Piezoresistance and Quantum Confinement in Microcrystalline Silicon

ABSTRACTWe report piezoresistance studies in microcrystalline silicon films produced by reactive sputtering from a silicon target in an atmosphere of hydrogen and argon. The microcrystalline silicon films are two phase materials consisting of 50-100Å diameter silicon crystallites embedded in an amorphous Si-Hx matrix. The conductivity of the films was found to decrease significantly when the films were put under compression. Conductivity decreases of up to 100% were observed; this large conductivity changes with strain indicate that microcrystalline silicon is ideally suited for highly sensitive strain gauge applications. The results can be qualitatively accounted for in a model which assumes quantum confinement of carriers in 50Å diameter silicon crystallites separated by tunnelable amorphous Si-Hx barriers.

A new instrument for serial measurements of elasticity in hypertrophic scar.

The "elastometer," a hand-held device, was designed and constructed to permit noninvasive quantification of the elastic properties of normal skin or hypertrophic scar. The instrument utilizes a constant-tension spring and a sensitive strain gauge to distract two loci of skin. Normal skin from 15 dogs was measured in vivo with the elastometer and in vitro using standard tensometry. The results correlated significantly by regression analysis (r = .87, p less than .01, 1/Young's Modulus of Elasticity v percent stretch in vivo). Normal dorsal hand skin was tested elastometrically in six volunteers of both sexes. Values (units: percent stretch) ranged from 29 to 43 with a small standard error (+/- 4%). In nine patients with hypertrophic burn scars, the mean percent stretch was 16.2 +/- 1.8 v 37.9 +/- 6.5 in the mirror-image normal skin. There was no overlap between the two groups. There was a trend towards higher values in older scars. Elastometric measurements have increased appreciably in some burn scars undergoing treatment. The elastometer should be useful in documenting objectively the spontaneous maturation of burn scars and/or their response to treatment.

Pressure-pain threshold in human temporal region. Evaluation of a new pressure algometer

A hand-held pressure algometer with a pressure sensitive strain gauge at the tip was used to measure the pressure-pain threshold (PPT) in the temporal region of healthy volunteers. Various sizes of circular tips and various application rates were tested before selecting an area of 0.5 cm 2 and a constant application rate of 0.68 N · sec -1 for future use. A highly significant correlation was found between PPT values obtained from the two sides (of the head) ( P < 0.001) and between PPT values obtained with a 3-week interval ( P < 0.001). In a series of 50 immediate consecutive measurements in the same individual, the mean PPT was 171 kP a (N = 6, 2 S.D. 24%). The mean relative change in PPT after a 3-week interval was 0 ± 51% (N = 11, 2 S.D.). In the course of 5 repeated determinations at weekly intervals there was a significant increase in PPT (ANOVA, P < 0.05). Subcutaneous lignocaine significantly elevated PPT compared to placebo. Due to the high inter-individual variation, determinations of PPT for group comparisons should include rather large population samples, whereas in paired studies, the intra-individual variation allows the investigation of much smaller groups (10–20 subjects). It is our experience that the pressure algometer is easy to operate in the hands of a skilled laboratory assistant.

Performance test of a mechanical impedance gauge based on strain measurement on a rod

An impedance gauge based on measurement of strains at two cross sections of a slender rod has been tested on practical objects. Sensitive semiconductor strain gauges are used and the impact force n ...

Study of Electromechanical Activity of the Stomach in Humans and in Dogs With Particular Attention to Tachygastria

The relationship between electric and mechanical activities of the gastric antrum was investigated in both humans and dogs. In 2 patients, in whom platinum monopolar electrodes were implanted on the serosal surface of the antrum and a perfused manometric tube was placed in the stomach, the number of gastric contractions detected by manometry was only less than 50% of the pacesetter potentials accompanied by action potentials or second potentials. No contraction of the stomach was recorded by manometry when pacesetter potentials occurred without action potentials or second potentials. The relationship was further investigated in 11 anesthetized dogs prepared with implanted electrodes and sensitive ministrain gauges implanted on the serosal surface of the stomach and an intragastric manometric tube. In these dogs, phasic contractions were always recorded by the method using ministrain gauges although the electrical activity showed only PSPs without action potentials or second potentials. The manometry, however, could not recognize these phasic contractions. When the stomach was stimulated by bethanechol infusion through the splenic artery, as in the human stomach, the manometry detected less than 50% of gastric contractions detected by the strain gauge recording. The gastric dysrhythmia including tachygastria, tachyarrhythmia, and bradygastria was induced in 10 dogs by epinephrine, 100 micrograms X kg-1 X h-1, infused via the splenic artery. During the period of gastric dysrhythmia, the phasic contractions disappeared and no contraction associated with action potential could be observed. The phasic contractions reappeared as long as the PSPs occurred regularly in a frequency of 4-5 cycles/min during either the control period or during the period of epinephrine infusion. The epinephrine-induced gastric dysrhythmia was blocked or reversed to normal pacesetter potentials by intraarterial infusion of phentolamine. Our study suggests the following: (1) the pacesetter potentials not only pace and direct gastric contraction, but they may also play a role in the genesis of phasic contractions of the stomach, and (2) gastric contractions detected by sensitive strain gauges are not always recorded by the intraluminal manometry and, thus, gastric dysrhythmia may not be detected by the manometry in humans.

Simple and sensitive strain gauge displacement transducer

We describe a simple and sensitive strain gauge displacement transducer. It is based on the linear movement of a shaft (with two cantilevers and four strain gauges) in a tapered chamber, resulting in a change in resistance proportional to the cantilever deformation. The transducer with its Wheatstone full bridge configuration is calibrated against a mechanical dial indicator of 0.002 mm accuracy for both ac and dc voltage excitations. Its output is linear for measurements of full range displacement up to 25 mm. It has a sensitivity of ±0.0082 mm for ac excitation with a strain indicator whose resolution is ±1 με. It has a dc full range sensitivity of 1.5 mV/V for excitation levels up to 5 V. It can have varied field and laboratory applications wherever displacements are precisely read, recorded, or monitored.

The Exoskeleton and Insect Proprioception. I. Responses of Tibial Campaniform Sensilla to External and Muscle-Generated Forces in the American Cockroach, Periplaneta Americana

ABSTRACT The tibial campaniform sensilla are a group of mechanoreceptors in the cockroach leg that respond to cuticular strain. Each sensillum consists of a single bipolar neurone whose dendrite inserts into an ovoid cuticular cap embedded in the exoskeleton. The tibial campaniform sensilla are consistently separable into two subgroups with mutually perpendicular cap orientation: the long axis of the caps of proximal subgroups are oriented perpendicular to the tibial long axis; caps of the distal subgroup are parallel to the tibia. The responses of individual, identified sensilla from both subgroups were tested to the following forces: bending forces (perpendicular to the leg long axis), axial forces (parallel to the leg axis), torques (twisting about the leg long axis) and forces generated by the tibial muscles. The tibial campaniform sensilla respond vigorously to bending forces imposed in the plane of movement of the adjacent femorotibial joint. Individual sensilla exhibit orientation-dependent directional sensitivity in their response: the proximal sensilla respond only to dorsal bending; the distal sensilla respond only to ventral bending. Sensilla respond less vigorously to bending forces in other planes. Responses are weak but directionally sensitive to axial forces: the proximal sensilla fire upon axial compression; the distal sensilla fire upon axial tension. Both subgroups respond simultaneously but weakly to imposed torques. Contractions of the tibial muscles produce strong orientationdependent responses: the proximal sensilla respond only to flexor muscle contractions; the distal sensilla respond only to extensor muscle contractions. These responses are accurately predicted from a simple model in which the tibia behaves as a cylinder under stress. The tibial campaniform sensilla respond as directionally sensitive strain gauges. Each individual sensillum responds only to compressions perpendicular to the long axis of its cuticular cap. Tibial campaniform sensilla respond best to those forces that the animal can most effectively control.

Colonic motility in the cat. 3. Influence of hypothalamic and mesencephalic stimulation.

AbstractRostad. H. Colonic motility in the cat. III. Influence of hypothalamic and mesencephalic stimulation. Acta physiol. scand. 1973. 89. 104–115.Colonic motility recorded with sensitive extraluminal strain gage transducers was studied in lightly anesthetized cats following electrical stimulation of hypothalamic, and mesencephalic structures. Stimulation of various structures of the hypothalamus produced the following: 1) The sympatho‐inhibitory area in the anterior hypothalamus increased colonic activity concomitantly with a fall in blood pressure. 2) The ventral anterior and lateral hypothalamus produced excitatory colonic effects, but these were usually associated with a rise in blood pressure. Similar effects were obtained from the dorsal part of the ventromedial hypothalamic nucleus. 3) Stimulation of the ventral part of the hypothalamus, mainly corresponding to the course of the medial forebrain bundle, and the ventral part of the ventromedial nucleus, resulted in inhibitory colonic effects. Stimulation of various structures of the mesencephalon produced the following: 1) The central gray substance, red nucleus and reticular substance elicited increased colonic effects, most conspicuous in the proximal part of the colon. These responses were usually associated with a blood pressure rise. 2) Points within the central tegmental tract and the medial lemniscus resulted in inhibition of colonic motility. The. functional significance of the results and their relation to behavioural patterns are discussed.

Colonic motility in the cat. II. Extrinsic nervous control.

AbstractRostad Colonic motility in the cat. 11. Extrinsic nervous control. Acta physiol. scand. 1973. 89. 91–103.Experiments were performed on cats lightly anesthetized with pentobarbital sodium and a neuromuscular blocking agent, pancuronium bromide, in order to study the distribution of the extrinsic colonic nerves and their influence on the motility of various parts of the colon. The motility was recorded in its proximal, middle and distal part with sensitive extraluminal strain gage transducers and arterial blood pressure and respiratory movements were recorded using pressure transducers. The influence of the extrinsic nerves on the colonic motility was investigated both by sectioning of the nerves and by electrical stimulation of the peripheral ends of the cut nerves. There was no marked functional differences between the proximal and distal portions of the colon. The vagal and splanchnic nerves, containing pure motor and inhibitory fibres, respectively, have their functional distribution throughout the greater part of the colon, although most marked in the proximal part. The parasympathetic pelvic, nerves supply the whole colon with motor fibres. At just suprathreshold stimulation of these nerves the responses in the proximal part of the colon were of lower amplitude and longer latency than in the remaining portions. The sympathetic lumbar colonic nerves distribute to all parts of the colon with mainly inhibitory fibres, but have some excitatory fibres as well.

A Discussion on the measurement and interpretation of changes of strain in the Earth - Dislocation models for fault creep processes

Tectonic processes in the lithosphere are plastic-elastic phenomena, in which the processes of plastic yield are in general inhomogeneous, and often strongly localized in faults, but then still, of course, at any one time inhomogeneous over the area of the fault. Motion on a fault may either be rare, sudden and seismic (stick-slip) or frequent and virtually aseismic (creep). Associated with these localized plastic strains, and dependent on their inhomogeneity, there are small elastic strains in the surrounding medium, in which sensitive strain gauges distributed over the surface, away from the fault, can give information about the inhomogeneities of plastic strain below the surface. Present needs are above all to have Earth-strain gauges giving significant continuous records over a period of years, cheap enough and sufficiently undemanding in site requirement to permit installation in considerable numbers for the observation of one tectonic or pre-seismic phenomenon, and to learn their habits and how to separate tectonically significant signals from various kinds of noise, e.g. of hydrologic origin. In planning such a layout, say, near to a strike-slip fault known to have creep activity, one sensibly assumes some simple model or models for the kind of motions on the fault which are to be looked for, and whose elastic consequences can be readily calculated. Single line dislocations moving on the fault provide such models, and enable one to see that features of the fault motion will be indicated by strain gauges in particular orientation. For example, if a travelling creep event is represented by vertical edge dislocation lines, strain gauges parallel to or perpendicular to the fault have their merits for resolving their distribution on the fault, but a strain gauge at 45° will see it coming from a greater distance (e.g. will see a slip-event of magnitude 1 mm when it is 10 km away, if a strain of 10-8 can be distinguished from noise), and will also respond to slip events which correspond to the rise of screw dislocations from below, which will not be noticed on strain gauges in the other two orientations. Gradually accumulating screw dislocations at depth make a reasonable tentative mode for the stress build up preceding an eathquake.

High Fluid Potentials in California Coast Ranges and Their Tectonic Significance

High Fluid Potentials in California Coast Ranges and Their Tectonic Significance

A method for the remote determination of the displacement amplitude of an ultrasonic horn

An indirect method for the determination of the face displacement of an ultrasonic stepped horn is described. Accurate determinations of displacement were first obtained by an interferometer method and these were then calibrated against the output of a sensitive miniature strain gauge. Subsequent determinations of displacement could then be made when the horn tip was obscured as in ultrasonic atomization.

Measurement of(∂P∂T)Vand Related Properties in Solidified Gases. II. SolidH2

We report measurements and their analysis of pressure changes with temperature and ortho-${\mathrm{H}}_{2}$ concentration in solid ${\mathrm{H}}_{2}$ in both the hcp and cubic phases. The temperature range extended from 0.4 to 4.2\ifmmode^\circ\else\textdegree\fi{}K, and the concentration $c$ of ortho-${\mathrm{H}}_{2}$ was between 0.005 and 0.94. The measurements were carried out by means of a sensitive capacitance strain gauge capable of resolving pressure changes of 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ bar. The categories of experiments performed were (1) determination of the pressure $P$ in the hcp phase as a function of ortho concentration at several temperatures; (2) determination of the pressure difference $P (\mathrm{hcp})\ensuremath{-}P (\mathrm{cubic})$ as a function of ortho concentration, and study of the hysteresis in both pressure and temperature of the hcp-to-cubic transition; and (3) measurement of ${(\frac{\ensuremath{\partial}P}{\ensuremath{\partial}T})}_{V}$ at constant ortho concentration in the hcp phase at several different ortho concentrations. The results were analyzed in terms of a lattice contribution and an electric quadrupole-quadrupole (EQQ) interaction, neglecting any effects from other interactions and from crystalline fields. The EQQ interaction parameter determined experimentally was $\ensuremath{\Gamma}=\frac{6{e}^{2}{Q}^{2}}{25{R}^{5}}$, where $\mathrm{eQ}$ is the quadrupole moment of the orthomolecule in the state $J=1$, and $R$ is the nearest-neighbor distance. The theoretical value for a rigid lattice is $\frac{\ensuremath{\Gamma}}{{k}_{B}}=1.00$\ifmmode^\circ\else\textdegree\fi{}K. The results from (1) and (2), extrapolated to pure ortho-${\mathrm{H}}_{2}$, were analyzed using the theory of Miyagi and Nakamura and gave $\frac{\ensuremath{\Gamma}}{{k}_{B}}=0.82\ifmmode\pm\else\textpm\fi{}0.04$\ifmmode^\circ\else\textdegree\fi{}K (value extrapolated to $P=0$). This value was confirmed from the temperature of the maximum of ${(\frac{\ensuremath{\partial}P}{\ensuremath{\partial}T})}_{V}$ at low ortho concentrations. The discrepancy between the experimental and the theoretical values of $\ensuremath{\Gamma}$ is briefly discussed. From ${(\frac{\ensuremath{\partial}P}{\ensuremath{\partial}T})}_{V}$ data with almost pure para-${\mathrm{H}}_{2}$ and from comparison with specific-heat data due to Ahlers, a lattice Gr\"uneisen constant ${\ensuremath{\gamma}}_{L}=2.06\ifmmode\pm\else\textpm\fi{}0.1$ was found. The Gr\"uneisen constant of the EQQ interaction was found to be ${\ensuremath{\gamma}}_{\mathrm{EQQ}}=1.62\ifmmode\pm\else\textpm\fi{}0.1$, in agreement with the theoretically expected value. Evidence was found for redistribution of orthomolecules at low ortho concentration as a function of time. The theoretical expectations for a thermodynamic-equilibrium distribution of molecules in the lattice and that for a random high-temperature distribution are compared with experimental results.

Compressibility, Thermal Expansion, and Other Properties of Helium-Three

Measurements of pressure versus temperature of solid ${\mathrm{He}}^{3}$ have been made for various constant volumes between 17.6 and 24.7 ${\mathrm{cm}}^{3}$/mole, in the temperature range from 0.35\ifmmode^\circ\else\textdegree\fi{}K to the melting point. Use was made of a sensitive capacitive strain gauge, which is described. From the pressure, the compressibility and thermal expansion coefficient are obtained. By extending the isochores into the liquid region, these quantities are also obtained for the liquid at melting. The compressibilities of the solid and liquid in equilibrium at the melting curve are nearly equal. The expansion coefficient of the solid is positive in the range investigated. Comparison with specific heats and with other results is made, and values of the Gr\"uneisen $\ensuremath{\gamma}$ and Debye $\ensuremath{\theta}$ are obtained. A discontinuity in volume of about 0.1 ${\mathrm{cm}}^{3}$/mole at the bcc-hcp phase transition down to 0.35\ifmmode^\circ\else\textdegree\fi{}K was found.

THE CONCURRENCE OF FINE MUSCLE ACTIVITY AND RAPID EYE MOVEMENTS DURING SLEEP.

Body movements were detected by means of highly sensitive semiconductor strain gauges on 10 subjects who slept overnight in a dream laboratory. Continuous measurement of movement from the eye, throat, hand, and foot indicated that activation was an integrated process which appears simultaneously from all locations. Correlations of level of eye movement activity and average activity level from other points measured ranged between .55 and .85 for each of 10 subjects, with the majority exceeding .75. Body movement patterns correctly identified 32 of 41 peats of eye movement activity.

EFFECT OF ALTERATION OF SERUM POTASSIUM ON URETERAL PERISTALSIS.

KNOWLEDGE OF ureteral peristalsis has been inadequate because of the low sensitivity of the recording instruments used. The organs under study are small, and conventional instrumentation distorts their function. Although urine is transported through the urinary tract by means of force produced by the peristaltic activity of the smooth muscles of the ureteral wall, the details of hydrodynamics have escaped scrutiny. Sensitive electronic strain gauges are now available to record phasic pressure fluctuations with minimal volume changes. These are used with small-caliber, nonobstructing catheters to avoid retention of urine which complicated previous methods used to record ureteral peristalsis. This development has given new impetus to the study of the physiology and pathophysiology of the upper urinary tract. Experiments with this equipment demonstrate that the activity of the normal ureter is remarkably independent of impulses of neuromuscular origin and it is not influenced by the administration of drugs. Because potassium has