Dual-function, Reusable, and Flexible Thermal Interface for Kinetic Monitoring of In Vitro Bioassays

Kinetic monitoring in life sciences is predominantly performed using contactless optical techniques. Miniaturized electronic sensing alternatives typically require direct contact with the sample. We introduce a dual-function thermal actuator/sensor that uniquely combines microwell-independent temperature control of a modified microplate and simultaneous measurement of real-time changes in thermal effusivity, offering both electronic readout and contactless sensing. The performance is demonstrated by monitoring Escherichia coli (E. coli) growth and assessing the effect of cefotaxime (CTX) as a use-case application, benchmarking it against state-of-the-art optical techniques. By qualitative comparison of characteristic data features, we report that the thermal sensing modality showed an increased response signal compared to optical density (OD) measurements in interface-dominated processes, which can be observed under experimental conditions where metabolic or morphological adaptation happens in response to CTX. Additionally, we developed an autonomous full curve data analysis approach for modified Transient Plane Source (mTPS) data, offering high robustness and lower susceptibility to systematic errors and bias. Our technique emphasizes interface-dominant processes, thereby complementing the assessment of bulk properties obtained by traditional optical techniques. The developed thermal interface is reusable, highly integrable, low-cost, easy to use, non-contact, and label-free, offering a versatile platform for bioassay development and dynamic biological studies.