Abstract: A moisture content sensor for measuring the moisture content of a medium. The sensor includes a probe that injects an electrical signal into the medium. Complex impedance circuitry located between the probe and the electrical signal source allows sensing electronics to generate a signal that represents the moisture content within the medium based on changes in the permittivity of the medium. The complex impedance circuitry minimizes the influence of temperature and conductivity of the medium on the sensed signal. The sensing electronics may be adjusted to optimize the sensor for varying medium conditions and to vary the linearity of the response curve based on volumetric water content of the medium.

Abstract: A moisture content sensor comprising a signal source (400) arranged to provide a signal, a probe (9) arranged to inject the signal into a medium (6) in which the moisture content is to be measured, a complex impedance (4) placed between the probe (9) and the signal source (400) and sensing electronics (7) arranged to monitor the signal at a point between the signal source (400) and the complex impedance (4) and generate a primary measurement therefrom which is indicative of the moisture content of the medium (6).

Abstract: In a dielectrophoretic cell having an array of electrodes and means to apply electrical signals to the electrodes. The electrodes include a planar array of serpentine or zig-zag electrodes with their curvatures in register. The serpentine electrodes may be sinusoidal, half sinusoidal, or elongated “C” in shape. The positions of maximum curvature of each serpentine or zig-zag electrode may be arranged in linear alignment, or along a curve. The cell may be used for stationary or traveling wave dielectrophoresis. Particles traveling in opposite directions in traveling wave dielectrophoresis can do so without interference, allowing “traffic control”. Particles can be characterized and separated, and particles at high concentrations, or particles of different types, can be handled.

Abstract: In a method of manipulating particles suspended in a liquid medium, a moving standing wave ultrasonic vibration and an electrical field capable of generating a dielectrophoretic force on the particles are applied. The ultrasonic vibration may be applied to move the particles from a first suspending liquid to a second suspending liquid, or to move the particles into proximity with electrodes to apply the dielectrophoretic force, or to move the particles into the center of the liquid medium. Alternatively, the ultrasonic vibration and the electrical field may be applied simultaneously.

Abstract: A ring-wing aircraft suited particularly, although not exclusively, to use in micro-unmanned air vehicles (UAV's) with ring-wings. An aircraft (10) according to the invention comprises a ring-wing (11) defining a duct (16) with a longitudinally-extending central axis (31), propulsion element (15) located within the duct and moveable aerofoils (13, 18) for controlling the aircraft in flight, the ring-wing being truncated obliquely at one end, that end being the rear (11b) when in horizontal flight, to form a ring-wing with opposed sides of unequal length. This arrangement produces center of mass offset from the central axis of the ring-wing, the pendulum effect will ensure that the aircraft will roll so that its center of mass will always be at the lowest height possible when the aircraft is airborne. Therefore the aircraft has a preferred orientation, and the control surfaces can be oriented with respect to this preferred orientation.

Abstract: This invention relates to ring-wing aircraft and is suited particularly, although not exclusively, to use in micro-unmanned air vehicles (UAV's) with ring-wings.