On-chip inductive sensor for ultra-high-throughput integrated detection of oil contamination and viscosity

A novel on-chip inductive detection sensor has been developed, offering a new method for analyzing contaminants and viscosity in hydraulic oil. An ultra-high-throughput microchannel with a rectangular cross-section has been designed, along with a dual-core coil resonant method to generate a large-scale magnetic field with high sensitivity on the chip. The inductive sensing unit consists of two symmetrically arranged rectangular magnetic core coils, creating a detection area with a high magnetic field strength. A rectangular microchannel with a cross-sectional area of up to 6 mm² passes between the two magnetic core coils. Compared to traditional micro-inductive sensors, the throughput increased by nearly 2 orders of magnitude, reaching 120 mL/h. Using the microchannel and resonance measurement method, we successfully detected 30 μm iron particles and 80 μm copper particles. Furthermore, we have established a model that correlates oil viscosity with its transit time through the microchannel. Through the inductance signal, we can determine the time it takes for the oil to pass through the coils and subsequently calculate its viscosity using our theoretical model. This method allows for the integration of inductive detection and viscosity measurement without the need for additional sensor. In the experiment, we measured hydraulic oils of different viscosities and compared the results with measurements obtained using a viscometer to verify the accuracy of the viscosity measurements.