1.1.1. Operating arm. biosystems A15

1.1.1. Operating arm

This is a three-axis XYZ Cartesian mechanism. The X and Y axes move the dis pens ing needle over the analyser horizontally and the Z axis moves it vertically. It is operated by three step-by-step motors. In each 24-second preparation cycle, the operating arm performs the following actions: first of all, it sucks in the reagent from the corresponding bottle. Next, the needle is washed externally in the washing station and sucks in the sample from the corresponding tube. It is washed externally again and dispenses the sample and the reagent into the reactions rotor. Finally, it is exhaustively washed internally and externally before proceeding with the next preparation. The arm has a system for controlling vertical movement to detect whether or not the needle has collided into anything on descending. If a collision occurs, as may be the case if, for example, a lid has been left on a bottle of reagent, the arm automatically restarts, verifies the straightness of the needle and continues working issuing the corresponding alert to the user.

A vertical axis retention system prevents the needle from falling in the case of a power cut, avoiding injury from the needle to the user or the needle being bent by an attempt to move the arm manually. The operating arm only makes the preparations if the general cover of the analyser is closed. If the cover is raised while it is functioning, the arm automati cally aborts the task in progress and returns to its parked position to avoid injury to the user.

1.1.2. Dispensing system

This system consists of a thermostated needle, supported and displaced by an operating arm and conne ct ed to a dispensing pump. The needle is detachable to enable cleaning and replacement. The analyser has capacity level detection to control the level of the bottles and tubes and prevent the needle from penetrating too far into the corresponding liquids, thus minimising contamination. An automatic adjustment system informs the user if the needle is not mounted or if it is too bent. The needle has a sophisticated Peltier thermos tatation system, with PID control, capable of thermostating the preparations at approximately 37º in less than 15 seconds. Dispensing is carried out by means of a low maintenance ceramic piston pump driven by a step-by-step motor. It is capable of dispensing between 3 and

1250 ml. The exterior of the needle is kept cons tantly clean by a wash station included in the base. A membrane pump transports the waste to the corresponding container.

The A15 analyser has a tray with 4 free positions for racks of reag e nts or samples. Each reagents rack can carry up to 10 reagents in 20 ml or 50 ml bottles. Each samples rack can contain up to 24 tubes of samples. The samples can be patients, calibrators or controls. The analyser can be configured to work with 13 mm or 15 mm diameter tubes of samples with a length of up to 100 mm or with paediatric wells. Any possible configuration of racks can be mounted from 1 rack of reagents (10 reagents) and 3 racks of samples (72 samples) to 3 racks of reagents (30 reagents) and

1 rack of samples (24 samples).

On the left of the analyser are the waste and distilled water containers. The analyser constantly controls the level of these containers and issues the appropriate alerts if the distilled water is nearly empty or if the waste container is full.

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