Surface plasmon resonance (SPR)-based biosensors have recently been applied for cell detection. For quantitative interpretation of the SPR response from cell activities, an irregular-shaped homogeneous refractive index model was established. A simple but quantitative mathematical formalism was derived from the model for interpretation of the SPR response from living cell attachment. To validate the mathematical formalism, both SPR and microscopic imaging were used to monitor the dynamic attachment process of HeLa cells to the substrate for >48 h. The interpretation of the SPR response agreed with the cellular morphology changes observed by microscopy, demonstrating the validity of the theoretical SPR model. The SPR response further revealed that the dynamic attachment process of HeLa cells consisted of two phases: a spreading phase and a proliferation phase, with a negative-exponential confluency change of 5.28% and 24.56%, respectively. Additionally, quantitative SPR was applied for the detection of anticancer drug action kinetics. The dynamic attachment process of HeLa cells was monitored on treatment with different concentrations of Paclitaxel for >48 h. We observed distinct cellular attachment kinetics, revealing dose-dependent inhibition of HeLa cell proliferation by Paclitaxel.

•A curved top-wall flow cell is proposed to improve the response consistency in SPR array detection.•A universal mathematical relation between the mass transport rate and the flow cell height was established and the optimal flow cell geometry for analyte distribution uniformity was derived.•The actual flow regimes within the novel flow cell were confirmed by micro-PIV experiments and results agreed with expectations.•Goat-anti-rabbit IgG and rabbit IgG interaction experiments were performed on a SPR imaging system using both the novel and conventional flow cells.•The novel flow cell significantly reduced the coefficient of variance of association rate across the sensing surface.High spatially consistent responses are desired for the array-based biomolecular interaction analysis. The response consistency is dependent on the uniformity of mass transport rate. Based on theoretical analysis, we established a universal mathematical relation between the mass transport rate and the flow cell height. The optimal flow cell geometry for analyte distribution uniformity, H(l) = 1/3 · l−1/2, was derived from the mathematical relation. Using Poly(dimethylsiloxane) elastomer replica molding methods, the flow cell was fabricated. The actual flow regimes within the flow cell were confirmed by micro-PIV experiments and results agreed with expectations. To demonstrate the capability of this flow cell in improving spatial consistency of responses, goat-anti-rabbit IgG and rabbit IgG interaction experiments were performed on a home-built SPR imaging system. Results showed that the curved top-wall flow cell significantly reduced the coefficient of variance of association rate across the sensing surface.

This paper presents a frameless eddy current sensor for cryogenic displacement measurement, for instance, the monitoring of axial displacement in liquid propellant engine. The frameless sensor probe, which consists of flat spiral coils and long flat cables, is manufactured on a polyimide substrate directly using the flexible printed circuit board (FPCB) process. Manganese cooper, instead of general cooper, is used as the material for coil because of its thermal stability of conductivity in the low temperature. The developed frequency-modulated (FM) oscillator is used to improve sensitivity and stability. A cryogenic calibration system is designed and fabricated to verify the performance of the sensor. Experimental results show that the flat manganese cooper coil with frameless construction can be specific about the effect of low temperature. The sensor has good thermal stability, sensitivity, temporal stability and repeatability in the temperature range of 20–273 K. Moreover, the flat sensor is flexible to easily adhere inside of the axial bush to monitor the axial displacement in practice.