We have a winner!
The inventors have picked An aerogel more transparent by Michel Daubizit
as the winner for this competition. Here's what they had to say:
“We are pleased with the contribution made by the crowd. The application suggested and elaborated by Michel takes advantage of the unique features of our current micromixer, and so this distinguishes itself from other designs. And the idea is feasible as it is relatively easy to implement without requiring many other supporting techniques to be developed.”
- Dr Kim Wui Chee, ETPL
Liquids behave a bit strangely if you confine them in very narrow channels, as you do in microfluidics. One important effect of this small scale is that you get something called “laminar flow” – when two channels merge, the inputs from each simply flow alongside each other instead of mixing as you might expect. Not brilliant if you want those two inputs to react!
We have developed a simple, non-powered device that can be added in-line to convert this laminar flow to oscillatory flow, achieving effective mixing in milliseconds.
Diagram of a Y-junction with the micromixer embedded in one of the arms showing transition from laminar to turbulent flow and high-speed recording of mixing at a Y-junction.
As you can see below, the device contains an inlet, an outlet, and a fluid chamber with a stepped sidewall that holds an elastic diaphragm. When a liquid is pumped through the device above a certain pressure, spontaneous vibration of the diaphragm will be produced, thus changing the stable laminar flow to high-frequency oscillatory flow.
Schematic of the mixer depicting the deformation and oscillation of the elastic diaphragm at increasing pressures.
As no external actuators (such as piezoelectrics or magnetic systems) are involved, the structure of the device is very simple and can be easily fabricated at low cost (several US$ at large scales, 10s of US$ at low numbers). Other passive systems, which typically rely on complex static geometries, achieve much lower throughput and slower mixing (typically a few seconds). However, it’s important to note our device kicks the bucket after about a certain time (typically around 10h) of continuous use.
Sponsored by the Royal Society of Chemistry.
The device was developed during a fundamental study on techniques to enhance microfluidic mixing (which it’s very good at!), with only a few real-world applications (in synthetic chemistry) in mind. At the moment it’s mainly just a cool piece of technology looking for some problems to solve.
We are currently exploring its application for nanoparticles synthesis – however, it may potentially be used for a huge range of chemical or biological processes where rapid mixing of chemical reactants, bio-samples or other reagents is required.
And that’s where you come in. We’re interested in both commercial and academic applications of the technology. A great submission would:
- Derive a competitive advantage in a field from the device’s unique features, i.e. the fact it achieves rapid, high-throughput mixing without the use of external actuators (keeping in mind the device starts degrading after ca. 10h).
- Be specific in terms of technical implementation.
- Clearly outline the path to adoption: Which research groups/companies should we talk to? Would the device need to be altered? Who’d be the end user?
- Simple structure: the device makes use of the spontaneous vibration of the diaphragm; no actuators and controllers are involved.
- High oscillation frequency: typically ranges from several tens to several hundred Hz, achieving rapid mixing.
- Operable pressure range: 0.3 bar ~ 6.5 bar, applied via a pump or manually via a syringe. Higher pressure is required for higher viscosity liquids (viscosity ~60 cP (think olive oil) possible at 6.5bar)
- Chamber diameter 0.1 - 1 cm (note that this refers to the chamber diameter, not that of the flow channel, which will be significantly smaller) with flow rate 1.2 - 80 ml/min.
- Can make the chamber out of most materials (plastic, glass, metal…). The diaphragm must be elastic – rubber or, for high temperature applications (>100°C possible), spring metal
- Operable for a certain amount of time (10h for mid-range flow parameters), after which material degradation sets in because of the rapid oscillation.
- Device automatically acts as a pressure-limiting valve and one-way valve, i.e. blocks high-pressure and reverse flow respectively. However, can be designed to produce oscillatory flow in each direction.
The SIMTech Microfluidics Foundry (SMF) is established by the Singapore Institute of Manufacturing Technology (SIMTech), a research institute of the Agency for Science, Technology and Research (A*STAR), to advance the microfluidic technology as well as nurture and grow the microfluidics industry in Singapore by providing the infrastructure, support and manufacturing solutions to the academic and industrial community.
The Microfluidics Manufacturing Programme (MMP) is an application-oriented programme that harnesses the capabilities of SIMTech’s core technology groups to develop and implement a complete set of manufacturing processes for polymer-based microfluidic devices.
With Marblar, we hope we can speed up the movement of some of the exciting technologies we've developed from laboratory to market. Excited to see your ideas!
International patent application WO 2012/036627 A1
H. M. Xia et al., Converting steady laminar flow to oscillatory flow through a hydro-elasticity approach at micro scales, Lab Chip, 2012, 12, 60-64
Review on microfluidic mixing (background reading)