|Yes, it is Nobel season again and time for our annual George Whitesides plug, see earlier episodes here from 2011 and 2010. So what has his lab been up to this year?|
We have already seen oil droplets traversing a liquid maze but what about a especially designed maze for air bubbles?( DOI). At each branch in a microchannel network a bubble makes a binary choice (left / right) opting for the channel with the largest volumetric flow rate of the carrier liquid. As each bubble affects the flow rate of the channel it is in, the travelling behaviour of a bunch of bubbles tends to get very complex. The project aims to simulate the behaviour of red blood cells in blood vessels or a car in inner-city traffic. Surprise: a single bubble does not necessarily travel along the shortest path.
2012 also brought a new method for separation of gold nanoparticles (DOI). Desired nanorods and undesired nanospheres have the same density and regular centrifugation of nanogold solutions would be pointless. On the other hand, in a layered multiphase system the nanorods could be isolated based on a difference in viscosity. One such multilayered system is water-based Brij35 / oxazoline polymer / ficcol. After centrifugation, simple visual inspection gives away the location of the nanorods: the brown top Brij layer.
In 2010 Maglev technology for some reason was used to accurately measure the density of various brands of peanut butter. This year the application range has been extended to forensic science. Several brands of gunpowder (Hercules Blue Dot, IMR Trail Boss) can be differentiated using maglev. Regular glitter (!?) (Alpha Jewels I, Crystalina #321) was also included in the study (DOI). So if in a future episode of one of the many CSI franchises you see somebody levitating a sample you know where the invention came form.
The Whitesides lab has a continuing interest in keeping nematode worms in a lab-on-a-chip. Latest exploit with drug-screening potential: record an electrocardiogram of the throat section as the worm is having its drug-laced dinner (DOI). It definitely chokes on antiparasitic drug Ivermectin.
The soft polymer gripper that was featured in this blog in 2011 has evolved into a creepy multigait soft robot (DOI) that looks remarkably like a headless guy in a swimsuit (MOVIE!). The device reversibly contracts by letting air in and out through microchannels. In a second evolutionary step the robot has been fitted with camouflage thanks to an outer layer with microfluidic channels (DOI). The channel pattern and also the color of the dyes can be customised for a wide range of surfaces (carpet, leaf litter , rocks). Other variations are glow-in-the-dark-robots and by controlling the temperature the robot can be stand out in the infrared or even disappear from the infrared.