Level sensor and washer unit
First Claim
1. An automated immunoassay processing system including a level sensor, comprising:
- a head mounted for vertical movement, said head comprising an aspirate tip having an internal flow passage within and along which first and second electrode means are provided, each forming a part of the flow passage and being connected to a detector circuit arranged to give an output signal when the electrode means are bridged by fluid;
aspirating means connected to the aspirate tip;
a motor for moving the head;
a positioning circuit for controlling the motor to position the head at specified vertical positions; and
control means connected to receive the output signal of the detector circuit;
characterized in that;
the aspirating means is arranged to aspirate while the head is being lowered towards the surface of the fluid;
the first and second electrode means are insulated from each other and vertically positioned so that in use fluid passes through said first electrode means before passing through said second electrode means; and
the control means is arranged to produce an indication of the level or volume of fluid in a reaction cell by reference to a vertical position signal when the detector circuit gives an output signal on the aspirate tip coming into contract with fluid in the reaction cell and to generate an output indicating the presence of fluid passing between said first and second electrode means while the fluid is being aspirated from the reaction cell.
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Accused Products
Abstract
A fluid level sensor and a washer unit are provided for an automated immonoassay processing system. A washer head (13) is vertically movable by a drive (2) above a reaction tray (8) having fluid (15) in separate cells. The level sensor comprises two electrodes arranged along a fluid path within aspirator tips (6). The electrodes are held at different electrical potentials and are effectively insulated from each other. If fluid is aspirated along the fluid path then the electrodes are bridged. Control means (1) is arranged to detect any change in conductance between the electrodes thereby indicating the presence of fluid (15). The vertical height of the washer head is determined relative to the sample thereby enabling the device to determine the level of the fluid (15).
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Citations
9 Claims
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1. An automated immunoassay processing system including a level sensor, comprising:
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a head mounted for vertical movement, said head comprising an aspirate tip having an internal flow passage within and along which first and second electrode means are provided, each forming a part of the flow passage and being connected to a detector circuit arranged to give an output signal when the electrode means are bridged by fluid;
aspirating means connected to the aspirate tip;
a motor for moving the head;
a positioning circuit for controlling the motor to position the head at specified vertical positions; and
control means connected to receive the output signal of the detector circuit;
characterized in that;
the aspirating means is arranged to aspirate while the head is being lowered towards the surface of the fluid;
the first and second electrode means are insulated from each other and vertically positioned so that in use fluid passes through said first electrode means before passing through said second electrode means; and
the control means is arranged to produce an indication of the level or volume of fluid in a reaction cell by reference to a vertical position signal when the detector circuit gives an output signal on the aspirate tip coming into contract with fluid in the reaction cell and to generate an output indicating the presence of fluid passing between said first and second electrode means while the fluid is being aspirated from the reaction cell. - View Dependent Claims (2, 3, 4, 5)
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6. An automated immunoassay processing system including a level sensor, comprising:
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a head mounted for vertical movement, said head comprising an aspirate tip having an internal flow passage within and along which first and second electrode means are provided, the electrode means being connected to a detector circuit arranged to give an output signal when the electrode means are bridged by fluid;
aspirating means circuit for controlling the motor to position the head at specified vertical positions; and
control means connected to receive the output signal of the detector circuit;
characterized in that;
the aspirating means is arranged to aspirate while the head is being lowered towards the surface of the fluid;
the first and second electrode means are sequentially positioned so that in use fluid passes through said first electrode means before passing through said second electrode means; and
the control means is arranged to produce an indication of the level or volume of fluid in a reaction cell by reference to a vertical position signal when the detector circuit gives an output signal on the aspirate tip coming into contract with fluid in the reaction cell and to generate an output indicating the presence of fluid passing between said first and second electrode means while the fluid is being aspirated from the reaction cell, said head further comprising a;
dispensing tip arranged to dispense washing fluid into a reaction cell with both the dispensing and aspirate tips positioned above the cell, and wherein after the washing fluid is dispensed the aspirate tip is lowered while aspirating, the control means being arranged to produce an indication of the level of washing fluid when the aspirate tip reaches the fluid surface, whereby the dispensing of a correct quantity of washing fluid may be confirmed. - View Dependent Claims (7, 8)
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9. A method of sensing a level of fluid in a reaction cell of an automated immunoassay processing system comprising a head, first and second electrode means said electrode means being vertically spaced apart, and an aspirate tip comprising the steps of:
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lowering the head towards the reactions cell while generating a vertical position signal of said head relative to said cell;
aspirating while lowering the head;
outputting a signal from each of said electrode means when the first and second electrode means are bridged by fluid passing through said electrode means and aspirate tip;
producing an indication of the level of fluid in the reaction cell by reference to a vertical position signal when the aspirate tip comes into contract with fluid in the reaction cell; and
generating an output indicating presence of fluid passing between the first and second electrode means while the fluid is being aspirated from the reaction cell.
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Specification