British Technology Group Limited

University of Sheffield

Sheffield Teaching Hospitals Nhs Foundation Trust

Btg International Limited

Brian Hilton Brown

David C Barber

John Anthony Tidy

Dilichukwu Anumba

Francis Joseph McArdle

Ian Leslie Freeston

Apparatus for determining the electrical conductivity of target cervical tissue using magnetic impedance spectroscopy comprising: an excitation coil for producing a magnetic field which is capable of inducing currents in the target cervical tissue; a gradiometer for detecting perturbations in said magnetic field caused by said induced currents, the gradiometer including screening means for minimising sensitivity to tissues other than the target tissue; processing means for determining an electrical conductivity of said target cervical tissue from said perturbations.

Apparatus and methods for determining electrical conductivity of tissue

Apparatus for measuring the electrical impedance of a tissue sample comprises a probe and a sheath comprising an elongated tubular body having one closed end and one open end providing an internal cavity. The sheath is composed of a material which when contacted with a tissue sample is capable of providing a conductive path through the sheath between the electrodes and the tissue sample. The resistivity of the material forming the sheath when contacted with the tissue sample is greater than the resistivity of the tissue sample. The probe is received within the internal cavity of the sheath. The sheath is impervious to bacteria and viruses.

Apparatus for measuring tissue samples electrical impedance

A method for determining whether a probe for measuring the impedance of human or animal body tissue has been placed over a boundary between different tissue types is described. The probe used in the method comprises at least a first (), a second (), a third () and a fourth () electrode arranged such that the third () and fourth () electrodes are each located substantially the same distance from both the first () and second () electrodes. The method comprises: driving a current between the first () and the second () electrodes; measuring a first value of an electrical parameter between the third () and the fourth () electrode; and determining whether the probe has been placed over a boundary between different tissue types based on the first value. A probe for carrying out the method is also described.

Method and probe for measuring the impedance of human or animal body tissue

The invention concerns a method and apparatus for monitoring respiratory condition by impedance pneumography. An electrical signal is applied at a plurality of frequencies to a human subject by way of a first pair of spaced electrodes applied to the trunk of the body, whilst the resulting electrical signal is monitored at the plurality of frequencies at different points on the body by way of a second pair of spaced electrodes. From the resulting electrical signal a measure of the impedance of a part of the body at the plurality of frequencies is obtained, and a difference signal representing the impedance change with frequency is calculated. The difference signal is normalized with respect to a signal representative of the impedance measure itself at one or more frequencies, thereby suppressing the effect of those impedance signal components--such as movement artifact--whose frequency dependent change is substantially proportional to the impedance signal value. The invention improves the reliability of impedance pneumography, especially when employed in situations in which it is difficult to restrict subject movement, such as during sleep. It has particular application in neonatal and infant sleep apnea detection systems.

Impedance pneumography

Investigation of a body

Image reconstruction

Electrical impedance tomography

Applied potential tomography

Real-time electrical impedance tomography system

A method of determining the external shape of a body comprises placing a plurality of electrodes adjacent the surface at spaced intervals around the body, causing currents to flow in the body by applying an electrical potential between pairs of electrodes in turn, measuring potentials between other pairs of electrodes, relating the measured potentials to the distances between the corresponding points of current introduction and of potential measurement, and determining electrode positions consistent with these distances, which electrode positions define the external shape of the body.

Tomographic images (I.sub.1 and I.sub.2) of a body are constructed by placing a plurality of surface electrodes (1 to 16) at spaced intervals on the body (M), causing currents to flow in the body, and measuring the potential between pairs of electrodes, calculating the potential in each case on the assumption that the body consists of one uniform medium, plotting the isopotentials corresponding to the calculated results to create a uniform image of the body, obtaining the ratio between the measured potential and the calculated potential in each case, and modifying the image in accordance with the respective ratios by increasing the impedance along an isopotential in proportion to a ratio greater than unity or decreasing the impedance in proportion to a ratio less than unity. The calculations of potentials and the obtaining of ratios are carried out using a computer and the plotting of the isopotentials is carried out by a visual display unit (VDU) and/or a print-out unit run off the computer. An additional method is provided for indicating a change of state in the body. This method includes the step of determining ratios between initial and subsequent measured actual potentials between electrodes.

Growing community of inventors

Sheffield, United Kingdom

Brian Hilton Brown