Allergies and autoimmune diseases are a growing global issue, increasing the demand for reliable and automated diagnostic instruments. Thermo Fisher Scientific uses capsule-based test systems where nestled capsules are dispensed automatically. Current dispensing units are mechanically complex, resulting in high manufacturing costs and limited serviceability. The aim of this study was therefore to develop and evaluate a mechanically simplified linear dispensing unit for a medical diagnostic instrument.

The study was conducted as a product development project in which several concept ideas were developed and evaluated through iterative prototyping. To ensure reliable dispensing, tests were performed directly in the Phadia 200 diagnostic instrument. Experimental measurements were also carried out to determine the required spring rate for the dispensing mechanism.

The developed dispensing unit achieved individual capsule dispensing using only a linear vertical motion. The design reduced mechanical complexity compared to existing solutions, improving both manufacturability and serviceability. A total of 2016 dispensing cycles were performed. All dispensing cycles were successful, and no double dispensing was observed during testing.

The resulting design demonstrates that reliable dispensing can be achieved with significantly lower mechanical complexity and manufacturing costs compared to current solutions. With further testing and optimization, the design has the potential to replace complex dispensing systems used in existing analytical instruments.