Pneumatic Sensor Research Articles

Development of a sensor for non-invasive intracranial pressure measurement in the newborn

A new system has been developed for the non-invasive monitoring of intracranial pressure (ICP) across the anterior fontanelle in the newborn. The system comprises a very small pneumatic sensor linked via two vinyl tubes to an instrument where the ICP value is dislayed. The sensor is simply bonded to the anterior fontanelle, using industrial collodion normally used for attaching EEG electrodes. The sensor body is injection moulded in semi-flexible polyurethane with a very thin, compliant membrane bonded to its front surface. Using these manufacturing techniques the sensors are made to be disposable thus minimizing the risk of cross infection. ICP characteristics can now be recorded continously in a wide range of neonates and the evaluation of currently used therapeutic treatments for lowering elevated ICP can be carried out safely and accurately.

Pressure measurement in oesophageal varices: preliminary report on a new non-invasive method.

Pressure in oesophageal varices has been measured either by using an invasive puncture technique, or a non-invasive pneumatic pressure sensor. Experience with these techniques and their limitations prompted a new way of measuring pressure in oesophageal varices. This was done by observing through a transparent plastic balloon fixed to the tip of a gastroscope the pressure equilibrium between the varix and the balloon. One hundred measurements on an experimental model showed the reliability of the system. Measurements on eight patients with the balloon followed immediately by the puncture technique, showed good correlation.

Pneumatic primary sensor for measuring linear dimensions

Pneumatic primary sensor for measuring linear dimensions

Automatic Moisture Sensor for Measurement and Control of Cotton Ginning Processes

Cotton fiber moisture content is one of the most important factors that affects the operation of the cotton ginning process. A system has been developed that measures cotton’s dielectric constant and density with sufficient accuracy to indicate moisture content of the fiber during processing. An electronic capacitor and a pneumatic density sensor supply measurements to a microprocessor which combines them into a predicted moisture content. Tests showed that these predicted readings are more precise than conventional oven-moisture determinations and that they can be used for process control in the ranges from 6.5- to 12-percent moisture content.

Improvement in Accuracy of Pneumatic Delay

To reduce the probability distribution width of switching delay, it is necessary to use steep rise signals to the pneumatic devices. It is said conventional pneumatic delay of restrictor and capacitor combination causes ± 5 to 7 % errors, because signals rise slowly. To make the pneumatic delay accurate, the signals must rise steeply after the delayed time. A simple model for calculation shows one tenth reduction of error by using a soft flexible volume installed in a chamber. A new type inflating film capacitor was developed. The original film type can obtain ± 0.4 to 0.7 % errors, and a combination of film and pneumatic sensor gives ± 0.1 to 0.2 % in accuracy.

A New Liquid Level Sensor for Process-Control Applications

Many process-control systems are air-operated. In such an environment, it would be desirable and economical to use pneumatic sensors. Bubble-back pressure sensors perform quite satisfactorily, but in case of viscous inflammable and slurry-like liquids with a tendency to froth, this level sensor is inadequate. The method suggested in this paper utilizes a pneumatic capacitor, one boundary of which is formed by the liquid level, to modulate a fluid amplifier feedback oscillator. The absence of moving parts and economy obtained makes this method attractive for process-control applications. The system has been mathematically modeled and simulated on an IBM 360/44 digital computer. Experimental values compare fairly well with the theoretical results. For the range tested, the sensor is found to have a linear frequency variation with the liquid level Extended running in the laboratory shows that the system is very reliable. This system has been found insensitive to temperature variations of up to 15°C.

Pneumatic applanation tonometer studies. III. Analysis of the floating tip sensor

A theoretical and experimental study has been made of a pneumatic tonometric sensor designed to continuously record intraocular pressure and intraocular pulse. The tonometric probe includes a pneumatic bearing, which allows the sensor to float freely on a cushion of gas. Theoretical and experimental analyses have shown that it acts in a closely similar manner to the sensor without a gas bearing. Both can record the intraocular pressure with minimal volume disturbance of the eye and both can follow accurately experimentally induced modifications of pressure. However, they do differ in that the air-bearing means that the sensor is pushed against the cornea with a force of a few grams. This additional force causes a pressure increment in the eye of 1 or 2 mmHg above that induced by the rigid sensor, depending on whether the sensor is applied either horizontally (1 mmHg) or vertically ( ca. 2 mmHg) to the eye.

空気式センサをもつロボットハンドの位置探索

空気式センサをもつロボットハンドの位置探索

Automatic control of gap in thermal cutting machines by means of a pneumatic sensor

Automatic control of gap in thermal cutting machines by means of a pneumatic sensor

A pneumatic vortex angular rate sensor—Analysis and experiments

The performance characteristics of a vortex-type pneumatic angular rate sensor are presented. The porous coupling, used in all other vortex rate gyros, was replaced by a series of vanes and viscous coupling. A new pickoff system comprised of two spherical elements is introduced. The experimentally determined differential-pressure outputs compared favorably well with those predicted theoretically. Furthermore, the elimination of the porous coupling, the use of vanes and viscous coupling, and more importantly, the use of spherical pickoff elements have resulted in the increase of the sensor output, in the decrease of noise, in the elimination of the null-signal, and in the increase of the range of linearity of the sensor.

Selecting geometric dimensions for the flow part of a pneumatic sensor for fiberglass metric numbers

Selecting geometric dimensions for the flow part of a pneumatic sensor for fiberglass metric numbers

A Step-Bearing Accelerometer With Pneumatic Signal Output

A novel pneumatic acceleration sensor utilizing a single gas-bearing supported element is described. System damping and pneumatic signal output are obtained by reverse-flow flapper-nozzle valves which act as negative springs with respect to the inertial mass. Approximate design relationships for the static and dynamic performance of a two-axis accelerometer are presented. A prototype unit built to verify feasibility is described and experimental results are presented and compared with the analysis.