Abstract
The pharmaceutical industry has a unique problem of adopting new sensor technology to meet government regulations as well as very special processing demands. These dual forces are at work in the pharmaceutical industry, thus increasing the requirements for accurate and reliable sensors and associated instrumentation. Increasingly complex pharmaceutical processes require sophisticated instrumentation to create new or improved products and improve operational efficiencies.
This article examines the novel uses of ultrasonic technology in the sensors and instruments used in pharmaceutical processing. Included is an overview of the installation and application guidelines that can help manufacturers not only achieve the desired measurement accuracy, but also meet new requirements for government regulation.
The automated handling of large numbers of liquid samples is necessary in many pharmaceutical and chemical applications such as drug packaging and testing of various types of liquids such as blood reagents and laboratory assays. In such applications, the volume of the liquid in a large number of containers must be measured accurately on a high-speed basis. The samples are often in the micro-liter size in test tubes or vials having restricted size openings.
In a manual or semi-automated filling process, the liquid is aspirated into the containers using a pipetting technique and a measurement is made of the liquid level by inserting a probe into the container until it contacts the liquid. This is highly undesirable, particularly when the samples are contaminated, contain toxic liquids, or the sterility of the newly packaged product is to be preserved. Also, the step of making the measurement is relatively slow and sometimes produces inaccuracies.
A non-contact ultrasonic liquid level measuring system for products that are dispensed into small tubes, vials, micro plates and miniature vessels is more desirable. The system can operate on a single channel basis sequentially or on a multi-channel basis to measure sequentially, or in parallel, the amount of fill of a plurality of such tubes or micro plates.
A narrow beam of ultrasonic energy is transmitted from a sensor to the open top of an opposing tube to be reflected from the air-liquid interface of the tube back to the sensor. The round trip transit time of the energy is calculated. The height and inner diameter parameters of the tubes being measured are previously stored and a microprocessor uses this data and the measured round trip time to calculate the volume of liquid in the tube.
All of this is done without contact of any type with the liquid. The system can measure any tube or micro plate on an individual basis and there can be a single sensor below which a series of tubes held in a tray are passed one at a time. The measured volume data of all of the tubes is stored to produce a data map of the measurements.
For micro plates, the plurality of sensors of the bank are operated sequentially or in parallel and the calculated volume results are stored. In this manner, the volume data for the tubes in each row is mapped and has its own signature.
SOFTWARE AND HARDWARE TOOLS:
Software Tools:
- Keil compiler
- Orcad.
- Proload.
Hardware tools:
- AT89S52
- ULTROSNIC SENSOR
- LCD
- BUZZER
- FILLING PUMP
- MOTOR CONVEYOR
BLOCK DIAGRAM:
