Dr. Jürgen Spinke

Smart Reagent Dosing – novel cartridge concept for highly precise dispensing of IVD reagents down to the sub-µL range

Christoph Böhm, Thorsten Brückner, Timo Klein*, Peter Kupser, Nadine Losleben, Norbert Oranth, and Jürgen Spinke

Roche Diagnostics GmbH, Mannheim and *EXCO GmbH, Frankenthal

Driving forces for innovations in in-vitro diagnostic (IVD) are mainly improvements on the medical value for the patient and on the testing efficiency. The latter issue must be addressed without affecting the benefit for the patient. Increasing the testing efficiency and thus the economic advantage for the healthcare system can for example be achieved by a reduction of costs per result for IVD tests. One cost driving factor herein is the consumption of IVD reagents and disposables. This leads to a clear industry trend to reduce reagent volumes on future IVD systems by improving detection techniques and liquid handling robotics.

Most laboratory systems for IVD are based on using automated pipetting techniques for handling the liquid workflow, such as dosing of reagent. These pipetting techniques are well suited with respect to performance, accuracy, and precision for handling volumes above one µl. However, their use is limited in the sub µl range due to a reduced precision. Furthermore an increased effort to prevent carry-over of liquid on an automated analyzer is essential. Dispensing techniques, carry-over free by design, could overcome these limitations and potentially allow the handling of fractions of a µL by achieving the required dosing performance.

In this presentation a novel, contact-free dispensing technique is described, allowing for the highly precise dosing of IVD reagents down to the sub-µl range. All parts of the dispenser can be mass produced and allow for a favorable integration into disposable reagent containers (cartridges). Precisions smaller 2 % (CV) and accuracies smaller 5 % are achieved down to 250 nl for a representative set of samples covering the rheological landscape of real IVD reagents. The calibration of the dispenser is universal and independent from the reagent and its rheological properties due to the use of a direct displacement method. The dispensed volume is freely adjustable by an actuator and not limited by the dispenser technique. A highly improved onboard stability of the reagent compared to state of the art systems is expected due to the potential use of a completely closed reservoir.