Background
Accurate measurement of pressure in microfluidics is crucial for flow control, fluid characterization, and monitoring, but it faces challenges such as achieving sufficient resolution, non-invasiveness, and ease of use.
Sensor Design and Mechanism
Researchers from the University of Portsmouth (PSL) and Hokkaido University have designed a fully integrated multiplexed optical microfluidic pressure sensor that is decoupled from the flow path. This device can measure local pressure along any microchannel without altering the fluid geometry.
The sensing mechanism employs a hydrogel that compresses under soft mechanical actuation and changes color in response to pressure variations. A thin film separates the hydrogel from the circulating fluid in the microchannel, allowing for pressure measurement of different types of fluids without direct contact.
Operation and Performance
Using a color camera to image the gel through transparent PDMS allows for direct, simple, and non-contact determination of local fluid pressure. The detection limit is as low as 20 mbar, with a resolution of approximately 10 mbar. By adjusting the mechanical properties of the sensing unit, sensitivity and measurable pressure range can be optimized.
Two-Dimensional Mapping and Publication
The photonic gel has a short response time and high spatial resolution, enabling the acquisition of two-dimensional pressure or deformation maps. The research findings were published in “Color-switching hydrogels as integrated microfluidic pressure sensors” in Scientific Reports.