SIMPLE paper pumps (KU Leuven) - Raymond Pho
General Overview
Self-powered Imbibing Microfluidic Pump by Liquid Encapsulation (SIMPLE) is a microfluidic platform that was developed by MeBioS groups at KU Leuven, Belgium. This platform aims to address the need for cost efficient, robust, easy to use, and autonomous for point of care (POC) devices. SIMPLE mainly utilizes difference in pressure from one end of the device to the other to drive fluid flow within the microchannel structure [1].
Design
The SIMPLE platform has three main parts: Working liquid chamber, Analytical Chamber, and Porous material chamber. The device was activated simply by a fingertip press to prove ease of use. Upon activation, the working liquid was absorbed by the porous material, which created a reduce pressure that drove fluid flow of the sample in the analytical chamber. Various passive valves were located throughout the device to prevent controlled flow and leakage.
Working Liquid Chamber
The working liquid is injected into the working liquid inlet channel and filled the working liquid channel up to right before the porous material. The working fluid can be encapsulated by PSA foil for storage and contamination prevention. When activated, the working liquid is undergoes imbibition by the porous material to created reduced pressure to drive fluid flow throughout the device [2].
Analytical Chamber
The analytical chamber is where the sample fluid will be injected and flow will be induced upon activation and imbibition of the working liquid. The sample fluid sits in the sample inlet well until the pressure driven flow is induced [2].
Porous Material Chamber
The porous material chamber contains the medium that imbibes the working liquid to induce fluid flow. The porous material can be a variety of materials; the published method utilized paper for proof of concept. In the published method, circular sector geometries of the porous material were used in the design and it was shown that by varying the sector angle, fluid flow could be manipulated. Sample volumetric flowrates could be increased to hundred of μL [2].
The equation for Q, volumetric flow rate with respect to the sector angle is as follows:[2]
- [math]\displaystyle{ Q = (dV/dt)= (\theta_{c}/360) * \phi2\pi rh * (dr/dt) }[/math]
where:
- [math]\displaystyle{ Q }[/math] is the volumetric flow rate of sample fluid
- [math]\displaystyle{ \theta_{c} }[/math] is the sector angle
- [math]\displaystyle{ \phi }[/math] is the porosity of the material
- [math]\displaystyle{ r }[/math] is the wetting radius of the porous material
- [math]\displaystyle{ h }[/math] is the thickness of the porous material
Fabrication
The published method created devices a digital tabletop craft cutter. The microchannels were designed into pressure-sensitive adhesive (PSA) material. With the cut PSA material, it was placed in between two PVC layers that contains inlet and passive valve designs. The porous material was also inserted into the porous material chamber during this fabrication process [1].
Potential Applications
The published method of SIMPLE proves to be an easy-to-use platform that can directly translate to many POC applications and for remote locations with minimal resources. This platform can be easily fabricated and stored in advance for application. SIMPLE has been shown to be adaptable to a variety of applications such has pumping and detection of biological assays.
One published application was in the detection of creatinine in plasma samples. Creatinine is an important marker for chronic kidney disease. SIMPLE was integrated alongside a benchtop Creasensor to quantify levels of creatinine in the samples [5].
References
- Kokalj, T.; Park, Y.; Vencelj, M.; Jenko, M.; Lee, L. P. Self-Powered Imbibing Microfluidic Pump by Liquid Encapsulation: SIMPLE. Lab Chip 2014, 14 (22), 4329–4333. https://doi.org/10.1039/c4lc00920g.
- Dal Dosso, F.; Bondarenko, Y.; Kokalj, T.; Lammertyn, J. SIMPLE Analytical Model for Smart Microfluidic Chip Design. Sensors and Actuators A: Physical 2019, 287, 131–137. https://doi.org/10.1016/j.sna.2019.01.005.
- Yeh, E.-C.; Fu, C.-C.; Hu, L.; Thakur, R.; Feng, J.; Lee, L. P. Self-Powered Integrated Microfluidic Point-of-Care Low-Cost Enabling (SIMPLE) Chip. Science Advances 2017, 3 (3). https://doi.org/10.1126/sciadv.1501645.
- Elizalde, E.; Urteaga, R.; Berli, C. L. A. Rational Design of Capillary-Driven Flows for Paper-Based Microfluidics. Lab on a Chip 2015, 15 (10), 2173–2180. https://doi.org/10.1039/c4lc01487a.
- Dal Dosso, F.; Decrop, D.; Pérez-Ruiz, E.; Daems, D.; Agten, H.; Al-Ghezi, O.; Bollen, O.; Breukers, J.; De Rop, F.; Katsafadou, M.; Lepoudre, J.; Lyu, L.; Piron, P.; Saesen, R.; Sels, S.; Soenen, R.; Staljanssens, E.; Taraporewalla, J.; Kokalj, T.; Spasic, D. Creasensor: SIMPLE Technology for Creatinine Detection in Plasma. Analytica Chimica Acta 2018, 1000, 191–198. https://doi.org/10.1016/j.aca.2017.11.026.
