University of Strathclyde

John Jackson

Seyed A Angadjivand

An apparatus is disclosed for monitoring physiological parameters comprising a harness adapted to be worn by a human being and electrical circuitry connected to the harness for calculating physiological parameters in accordance with predetermined algorithms. The harness includes a band which extends around a trunk portion of the human being. The band comprises an inelastic portion and an elastic portion. The elastic portion incorporates an electro-conductive elastomeric means which has a resistance value which changes as a function of elongation of the elastic portion. The electrical circuitry connected to the elastomeric element calculates and displays various physiological parameters.

Apparatus for monitoring physiological parameters

A method of manufacturing an electro-conductive elastomeric material comprises mixing together silicone polymer gum, graphitic carbon particles, curing and cross-linking agents in the presence of an oil having a carbon chain length of at least 16 and having a high degree of mesogenicity, together with a volatile additive in which the oil and gum dissolve and/or disperse miscibly. The volatile additive may be Toluene, Chloroform, Tetrahydrofuran, n-Hexane or SBP3.

Electro-conductive elastomeric materials

An elastomeric electro-conductive device (10) capable of providing within a predetermined range of elastic elongation (.lambda.) of the device (10) sensory signals representative of elastic elongation (.lambda.) imposed on the device includes an elastomeric electro-conductive member (11) bonded to an elastomeric substrate (12). Member (11) and substrate (12) have substantially similar resistance-to-stretch characteristics .phi. within the predetermined range. On a Mooney Plot for (.lambda..sup.-1) values in the range 0.5 to 0.8 .phi. is substantially constant at 0.4 M Nm.sup.-2.

Electro-conductive elastomeric devices

A method of manufacturing an electro-conductive elastomeric material comprises the steps of mixing together a silicone polymer gum such as type C2501, graphitic carbon particles such as 55 micron particle size, a curing agent such as Silester O.S., and a cross-linking agent such as DBTL in the presence of a mesogenic oil which is synthetic, unsaturated, and has two oleic chains. The preferred oil is di-oleyl-oxalate.

An elastomeric electro-conductive device 10 for human/animal joint movement monitoring comprises a silicone polymer non-conductive substrate 11 carrying an elastomeric electro-conductive member 12 formed from silicone polymer loaded with graphite carbon particles. Conductor means 14A,14B enable connection of the device 10 to an electrical network and comprise lengths 15 of conductive silicone rubber adhesively secured at one end to member 12 by a body 18 of elastomeric bonding material. The body 18 and the member 12 have the same electrical characteristics and may have identical constituents and formulations.

Elastomeric electro-conductive devices

A system for monitoring bone union at a bone fracture (13) comprises a fracture cast sleeve (15) to the external surface of which is bonded a transducer (16). Transducer (16) is electrically-conductive and has an electrical resistance which varies with elastic extension and contraction of the transducer. The output of transducer (16) is applied via a resistance-sensitive network (18) to a data evaluating device (20) arranged to normalize signals received from transducer (16) with respect to the time interval during which that signal appears since the signal is of an impulse nature depending upon the rate at which the force is applied to the fracture (13). The normalized signal is further normalized having regard to the mass of the limb concerned and a plurality of such signals are stored in store (30) together with a data log from date data device (32) and these signals are fed to a trend evaluator (34) in order to predict the time interval before bone union occurs.

Apparatus and method for monitoring bone-fracture union

Electrically-conductive materials comprising silicone rubber in combination with carbon particles in graphitic form incorporate a vegetable oil additive to provide enhanced physical and electrical resistance properties. Electrical resistivity for stress loadings below 500 grammes per square millimeter is less than 500 ohm-meters and for step changes in stress is of the order of 1K ohms-cm. A large number of vegetable oils provide these characteristics in the materials when the vegetable oils are present in the material in the range of 10-30% by volume. Carbon loading may be in the range 50-90% when measured in carbon grammes weight in relation to the milliliter content of the volume of silicone rubber and vegetable oil.

Electrically-conductive materials

Apparatus is provided which enable the assessment of mobility of human and/or animal joints to be carried out. A flexible transducer includes a conductive elastomer which, when stretched, provides a change in an electrical output signal. The transducer is located over the joint to be investigated and during movement of the joint electrical signals from the transducer output which are a function of joint mobility, are produced. The signals are digitized and stored in a memory and are compared with a bank of data from normal and pathological subjects stored in a continuously updated memory. When the comparison locates the `best fit` between the joint movement and the stored data, the type of joint movement is classified and the result is presented on a visual display unit. The movement signal can be conditioned so that the angular displacement of the joint, the rate of joint movement, acceleration of the joint can be estimated and classified. The force produced by the joint can also be calculated using the acceleration and an estimate of the mass moved. This system permits the progress of an individual to be monitored and to identify joint movement characteristics in particular patient populations. The transducer, when combined in a composite unit with electrodes is also used to accurately assess the degree of neuromuscular activity during and after anaethesia.

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Lesmahagow, United Kingdom

John Jackson