Understanding Fast and Slow Signal Changes in a Competitive Particle-Based Continuous Biosensor

The development of continuous biosensing technologies requires studies on time-dependent changes in sensor properties because such changes can impact the analytical performance of the sensor. In previous work, we studied long-term changes of a continuous cortisol sensor based on particle motion, which highlighted the roles of molecular loss processes in the biosensor. In this work, we study a glycoalkaloid sensor and observe two characteristic behaviors, namely fast and slow signal changes. Experiments were performed with single-sided aging, motion pattern analysis, and different blocking conditions. The leading hypotheses from this paper are that (i) fast signal changes predominantly result from multivalent interactions between the particle and the sensing surface, and (ii) slow signal changes arise from the gradual dissociation of analogue molecules from the sensing surface. The results give pointers for enabling long-term continuous sensing using particle-based biosensors.