Abstract: The present invention relates to hollow elements prepared from alloys having shape memory characteristics and techniques for heating the elements to effect the martensite (or R-phase) to austenite transformation. In its most preferred embodiment, the invention relates to the use of shape memory alloys to prepare hollow springs or tubular beams, bending and torsional, and the preferred methods of heating the elements include passing an insulated resistance heating wire through the core thereof and applying a current, or applying two layers of coating to the inside or outside of the tube, one of which is insulating and the other of which is electrically conductive. In the latter example, application of current to the conductive coating will heat the element. It is also envisioned that hot fluid may be passed through the element as the heating technique.

Abstract: A pivotal electrical connector for connecting a shape memory alloy element in the form of a coil spring to a fixed member, the connector including a strip of electrically conductive material having a clip or a pair of legs for securing the connector to one of the coils of the element. A pair of holes may be provided in the strip through which the coil is threaded. A rotational connector is provided in the strip for engaging the fixed member.

Abstract: A capacitance humidity sensor according to the invention has a film core which is in contact with a pair of polymeric conductive layers bonded to opposite faces of the core. The core is made of a polymeric material having a dielectric constant which varies substantially linearly with humidity, such as a polyimide or polyparabanic acid. The conductive layers are made of a polymeric material, at least a portion of which includes sulfur atoms in the backbone chain and having conductive particles, such as carbon particles, dispersed therein. Such conductive layers provide superior performance and corrosion resistance in comparison to the metal films employed in the prior art and in comparison to cellulosic polymers containing conductive particles.

Abstract: A high temperature titanium-based shaped memory alloy contains from at least 0.1 at. % hafnium. Articles formed from the disclosed alloy have high transformation temperatures. The alloy of the invention can be successfully hot and cold worked to make articles such as springs and wires.

Abstract: A capacitance elastomeric pressure sensor includes top and bottom mounting plates arranged to support a pair of electrode layers. The first electrode layer is supported on the upper surface of a dielectric disc held by an upper mounting plate. The second electrode layer is located beneath the disc and includes a conductive elastomeric layer overlying an elastomeric support layer. In the preferred embodiment, the elastomer is a silicone elastomer and the conductive layer is formed by admixing a conductive carbon powder with the silicone. The sensor is particularly effective in sensing pressure changes in this low range, e.g. 0-1 inch of water. In the most preferred embodiment the elastomeric layer is prestrained for temperature compensation.

Abstract: A pivotal electrical connector for connecting a shape memory alloy element in the form of a coil spring to a fixed member, the connector including a strip of electrically conductive material having a clip or a pair of legs for securing the connector to one of the coils of the element. A pair of holes may be provided in the strip through which the coil is threaded. A rotational connector is provided in the strip for engaging the fixed member.

Abstract: A shape memory actuator for controlling the position of a control member, such as a damper plate in a duct, the actuator including first and second shape memory elements each having an austenite phase transition temperature above which each element assumes a predetermined memory shape and a lower phase which forms when said element is stretched from the predetermined memory shape, the first and second elements being connected to move the control member in different directions when one or the other of the elements are heated to a temperature above its austenite phase transition temperature and an electrical circuit for selectively raising the temperature of one or the other of the elements. The control member may be held in a position between full open and full closed by holding mechanisms which connect the actuator to the control member.

Abstract: A capacitance humidity sensor according to the invention has a dielectric film core which is in contact with a pair of polymeric conductive layers bonded to opposite faces of the core. The dielectric core is made of a polymeric material having a dielectric constant which varies substantially linearly with humidity, such as a polyimide or polyparabanic acid. The conductive layers are made of a polymeric material having conductive particles, such as carbon particles, dispersed therein. Such conductive layers provide superior performance and corrosion resistance in comparison to the metal films commonly employed in the prior art.

Abstract: A sensor chip subassembly for use in a transducer assembly includes a support member to which a pressure sensitive chip is elastically bonded at predetermined but spaced points to separate the chip from direct contact with the support member. The separation minimizes vibration and stress from being transmitted from the support member to the chip.

Abstract: A process for adjusting the physical and mechanical properties of a shape memory alloy member of a known chemical composition comprising the steps of increasing the internal stress level and forming said member to a desired configuration and heat treating said member at a selected memory imparting temperature.

Abstract: A perforated thermoplastic film with less than ideally shaped tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes forming a perforated thermoplastic film having tapered capillaries from a resin into which an effective amount of a polarizable, migrating surfactant has been blended therewith and then treating the perforated thermoplastic film with a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film and provide a film having a percent run off of from about zero to ten percent.The perforated film made in accordance with the invention has a much higher liquid transmission rate than similarly made non-surfactant treated perforated film having tapered capillaries which has been treated only with a corona discharge treatment. The latter may be conducted as the film is being formed and perforated.

Abstract: A perforated thermoplastic film with less than ideally shaped tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes forming a perforated thermoplastic film having tapered capillaries from a resin into which an effective amount of a polarizable, migrating surfactant has been blended therewith and then treating the perforated thermoplastic film with a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film and provide a film having a percent run off of from about zero to ten percent.The perforated film made in accordance with the invention has a much higher liquid transmission rate than similarly made non-surfactant treated perforated film having tapered capillaries which has been treated only with a corona discharge treatment. The latter may be conducted as the film is being formed and perforated.

Abstract: A sensing probe unit includes an electrically nonconductive polymeric layer charged with a permanent electric charge to form an electret and intimately bonded to a compensating metal electrode. In the fabrication, the polymeric layer is cleaned and the metal electrode affixed to one surface by vapor deposition, lamination or baking. The polymeric layer may also be applied by coating the electrode with dielectric particles and then heating the subassembly to fuse the particles into an integral layer and to bond the fused layer to the electrode. The subassembly is thermally destressed and the polymeric layer is thereafter charged by triboelectric charging, corona discharge or electron beam charging, or by liquid contact charging processes. In the latter, a Freon-type or other similar liquid having good wetting properties and high evaporation rate is used as a contact charging liquid which creates a particularly stable electret. The sensing probe is stored to prevent loss of charge and sensitivity.

Abstract: A perforated thermoplastic film with tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes subjecting a perforated thermoplastic film having tapered capillaries to a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film.The film made in accordance with the invention has a much higher liquid transmission rate than the perforated film of the prior art. Furthermore, the film may be treated with a corona discharge continuously as the film is being formed and perforated.

Abstract: A temperature sensor is fixedly attached to a thin, flexible disc-like metal plate with sufficient flexibility to conform to the general shape of a surface. The sensor may be thermocouple, a resistor, a semiconductor or other structure. This thin metal member has a low thermal capacity or mass and a relatively high degree of thermal conductance. A tubular insulating and elastic member is fixedly attached to the periphery of the plate and to a tubular housing having an attached handle. The housing functions as a support and an enclosure for the temperature sensitive unit, flexible connecting leads and the like. The elastic member permits the plate to pivot about the housing to move into complete surface engagement with the surface being monitored. The electrical wires connected to the temperature sensitive unit are relatively fine to minimize the thermal mass and capacity added to the unit. The wires are also flexible such that they do not interfere with movement of the plate.

Abstract: An air pollutant and/or fire combustion sensing apparatus includes a charged insulating sensing electrode layer establishing an electric field as the result of electric dipoles and/or electric monopoles in or on the sensing layer. The layer has a high surface and bulk resistivity. The layer has a minimal water absorption at environmental humidities. The electric field of the sensing layer creates electrostatic sensing reactions with the gaseous products of combustion and environmental pollution and produces an amplification of the charge detection characteristic to alter the charge of the electrode. In a capacitive sensor, the sensing layer is mounted within and in spaced relation to a ground shield member. The sensing layer is thereby exposed and produces a sensitive capacitive detector for sensing of a wide spectrum of combustion products and the like.