Abstract: A cartridge for apparatus for analysing a sample comprising a fluid as a flow cell for receiving the sample. The cell is formed from a substantially rigid support surface (102), a sensor comprising an electrical mechanical transducer (92), for example a wafer of quartz crystal and adhesive means, such as double sided adhesive tape (100) attaching the sensor to the support surface. The support surface and sensor are spaced from each other by a membrane, which may form part of the double sides adhesive tape so as to define the flow cell between the support surface and the sensor. The flow cell also has an opening (for example, 111) through which, in use, the sample passes. The sensor, forming part of the flow cell, comes into contact with the sample to enable the sample to be analysed.

Abstract: Analytical apparatus for analysing at least one substance has an array of sensors (1) driven by an electronic driver (14) for operating each sensor. The signals produced by the sensors are received by a receiver (82), and the apparatus includes one or more calibration elements connected to the driver and the receiver for enabling changes in parasitic losses in the apparatus to be determined. The invention is particularly applicable to apparatus in which the sensors are electrical-mechanical transducers, individually connectable (in sequence) to the driver and receiver by a corresponding array of switches forming part of an interface (4).

Abstract: An ocscillator circuit having: a) a piezoelectric crystal connected to a surface; b) a variable frequency generator for generating a driving signal which is supplied to the crystal to cause the crystal to oscillate, thereby causing the surface to oscillate; and, c) an analyser for monitoring the phase shift between the voltage across the crystal and the current flowing through it and, in response generating an adjustment signal which relates to the difference between the oscillation frequency and a resonant frequency of the crystal, the variable frequency generator being responsive to the adjustment signal to vary the frequency of the driving signal to cause the crystal to oscillate at the resonant frequency.

Abstract: An apparatus for separating an analyte from a mixture or for detecting an analyte or for determining the affinity, or a property related to affinity, between binding partners includes: a) a surface having the analyte or one of the binding partners immobilized thereon, in use; b) a transducer for oscillating the surface; c) a controller connected to the transducer for varying the amplitude and/or frequency of the oscillation to cause a dissociation event; and, d) an analyzer connected to the transducer for detecting an oscillation of the transducer due to the dissociation event. The controller includes an oscillator connected in a resonant circuit with the transducer such that the transducer oscillates at two frequencies simultaneously, one of these causing the transducer to oscillate the surface and the other being supplied as an output to the analyzer.

Abstract: The subject invention pertains to a method for determining the affinity between binding partners, or a property of one of the binding partners dependent on the affinity, comprising the steps of: (i) contacting the binding partners, one of which is immobilised on a surface; (ii) oscillating the surface at increasing amplitude; and (iii) detecting a dissociation event. An analogous method can be used to separate a target analyte from a composition. The subject invention also pertains to an apparatus for determining the affinity between binding partners, and comprises: a surface (10) having one binding partner (16) immobilised thereon; means for oscillating the surface at increasing amplitude; and means (14, 15) for detecting a dissociation event.

Abstract: A quartz crystal sensor cell in which the sensor is secured to the base of a well defining a test sample space by a layer of adhesive between the respective peripheral surfaces. Also a quartz crystal sensor cell is provided in which the quartz sensor crystal is inclined relative to the opposite surface of the test sample space. These constructions respectively improve distinctness of the “Q” peak and problems from reflected waves in the space.

Abstract: A piezoelectric resonator element of crystallographic point group 32, which can be operated as a thickness shear resonator contacting a carrier medium includes a singly rorated Y-cut (S1,S2) that is essentially rotated through an angle ?about the crystallographic x-axis, which differs from crystal cuts that are temperature-compensated in air or vacuum, wherein the cut has a negative temperatue coeffcient of the resonace frequency f(T) in a predetermined temperature range, preferably between 10° C. and 40° C., when there is no contact with the carrier medium, while the value of the linear temperature coeffcient a of resonance frequency in the same temperature range is less than 1 ppm/° C., preferably less than 0.5 ppm/° C. when the resonator is inb contact with the carrier medium. The resonator element (1) can additionally be provided with at least one layer sensitive to the parameter to be measured.

Abstract: An analytical apparatus, such as a quartz crystal microbalance, comprises a piezoelectric sensor and an oscillator circuit, coupled to the sensor, to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output. The oscillator circuit maintains a substantially constant drive signal to the piezoelectric sensor by an AGC (33) within a feedback loop of the oscillator. The gain control signal is used as an indication of the Q of the piezoelectric sensor. The drive signal to the sensor is made substantially sinusoidal by ensuring that all the elements in the feedback loop providing signal gain and attenuation are configured to operate in a substantially linear mode.