On-chip pressure sensor using single-layer concentric chambers

Abstract

A vision-based on-chip sensor for sensing local pressure inside a microfluidic device is proposed and evaluated in this paper. The local pressure is determined from the change of color intensity in the sensing chamber which is pre-filled with colored fluid. The working principle of the sensor is based on polydimethylsiloxane deformation. The pressure at the point of interest is guided into a deformation chamber, where the structural stiffness is softened by chamber geometry, and thus, the chamber deforms as a result of pressure changes. Such deformation is transmitted to the sensing chamber, a same-layer concentric inside the deformation chamber. The deformation in the sensing chamber causes the colored fluid flowing in or out the chamber and leads to different color intensity from the top view through a microscope. Experimental evaluations on static and dynamic responses by regulated input pressures were conducted. The correlation in static response is 0.97 while the dynamic responses are successfully observed up to 16 Hz. The greatest advantage is that the local pressure can be directly seen without any additional hardware or electricity. The whole sensor is on a single-layer microfluidic design, so that the fabrication is simple, consistent, and low-cost. The single-layer design also provides the convenience of easy integration for existing microfluidic systems.

An Easy Method for Pressure Measurement in Microchannels Using Trapped Air Compression in a One-End-Sealed Capillary

“…Third, pressure sensors can also be used for implantable pressure monitoring, such as blood, intraocular, and intracranial pressures [ 23 , 24 ]. However, due to the limited range of microchannel dimensions, it is very difficult to integrate an additional pressure-sensing functionality without disturbing the flow field [ 25 , 26 , 27 ]. Therefore, measuring pressure inside microchannels is challenging and novel methods are demanded [ 28 , 29 , 30 , 31 ].…”

“…Several methods have been proposed in the literature for pressure measurement inside microchannels [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. The majority of these published approaches are mechanical in nature and primarily use a membrane that deflects as a function of the applied pressure [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ].…”

Towards an Optimal Pressure Tap Design for Fluid-Flow Characterisation at Microscales

“…The most common pressure sensors used in microfluidics are capacitive [17] and piezoresistive [18,19,20]. Besides these, other variations, such as optical [21,22,23], vision-based [24] and resonant sensors, do exist. A general review of several pressure-sensing technologies for microdevices can be found in Eaton and Smith [25].…”

Polydimethylsiloxane (PDMS)-based microfluidic channel with integrated commercial pressure sensors

“…Hence, there are many examples of the integration of a number of different types of pressure sensors with PDMS [7][8][9][10][11][12][13][14][15][16]. In these cases the reported pressure sensors have been custom made and involve multi-step microsystem fabrication processes, adding an element of considerable complexity.…”

“…This paper demonstrates that commercial pressure sensors can monitor the subtle pressure changes associated with the individual features of two important boiling modes and is suitable for characterising boiling in microchannels. This approach can also be adapted to address other applications for which bespoke sensors have been developed; i.e cell-culture [8], DNA and cell biology studies [15], chemical mixing, reaction, extraction, separation [10], characterisation of industrial fluids such as lubricants and coatings [14] and particle sorting and separation [16].…”