ALLPCB
Background
Precise measurement of pressure in microfluidic flows is essential 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 PSL University and Hokkaido University designed a fully integrated, multiplexed optical microfluidic pressure sensor that is decoupled from the flow path. The device enables local pressure measurements along arbitrary microchannels without altering the fluid geometry.
The sensing mechanism uses a hydrogel that compresses under soft mechanical actuation and changes color as pressure varies. A thin membrane separates the hydrogel from the circulating fluid in the microchannel, allowing pressure measurement for different fluid types without direct contact.
Operation and performance
Imaging the gel through transparent PDMS with a color camera provides a direct, simple, non-contact determination of the local fluid pressure. The detection limit is as low as 20 mbar, with a resolution of approximately 10 mbar. Sensitivity and the measurable pressure range can be optimized by adjusting the mechanical properties of the sensing units.
2D mapping and publication
The photonic gel's short response time and high spatial resolution enable acquisition of two-dimensional pressure or deformation maps. The work was published in Scientific Reports as "Color-switching hydrogels as integrated microfluidic pressure sensors".
