Patent ID: 9610584
Date: 2017-04-04
CPC Classifications: B01L,C12M,G01N

Claim:
1. Fluid testing apparatus comprising: a measurement chamber having a binding site to which can attach magnetic particles which have become associated with a target substance in the fluid; an oscillator circuit comprising an inductance and a variable capacitance in resonant combination to set the frequency of the circuit's output signal; a detector configured to generate a signal for altering the variable capacitance, wherein the inductance is influenced by the quantity of magnetic particles at the binding site and the detector is configured to generate a signal to alter the variable capacitance to maintain the frequency of the circuit's output in the face of changes in the quantity of magnetic particles at the binding site; a magnet that is enclosed within a first cavity of the fluid testing apparatus and slidably mounted within the first cavity so as to follow a predetermined path which maintains a pole face of the magnet substantially parallel to a binding surface of the measurement chamber such that magnetic particles orientate themselves in a manner that allows them to move towards the binding surface; and a control unit configured to issue control signals to move the magnet from a first position to a second position, wherein when the magnet is in the first position the fluid testing apparatus is operable in a first state in which the magnetic particles interact with the fluid such that magnetic particles become associated with the target substance in the fluid, and when the magnet is in the second position, the magnet is configured to generate a magnetic field within the measurement chamber to cause the apparatus to operate in a second state in which the magnetic particles are drawn to collect on the binding site, and wherein the control unit is configured to issue a control signal to move the magnet to the second position after a period of operation in the first state.