Improving the sensitivity and ultimately the range of particle sizes that can be detected with a single pore extends the versatility of the Coulter counting technique. Here, to enable a pore to have greater sensitivity, we have developed and tested a novel differential resistive pulse sensing (DiS) system for sizing particles. To do this, the response was generated through a time shift approach utilizing a “self-servoing regime” to enable the final signal to operate with a zero background in the absence of particle translocation. The detection and characterization of a series of polystyrene particles, forced to translocate through a cylindrical glass microchannel (GMC) by a suitable static pressure difference using this approach, is demonstrated. An analytical response, which scales with the size of the particles employed, was verified. Parasitic capacitive effects are discussed; however, translocations on the millisecond time scale can be detected with high sensitivity and accuracy using the approach described.

Microbubbles skate over a surface then through a microchannel where they continue to oscillate in response to the sound field.

Nanobubbles are fascinating but controversial objects. Although there is strong evidence for the existence of surface bound nanobubbles, the possibility of stable nanobubbles in the bulk remains in question. In this work, we show how ultrasonication of electrolytes can create transient bulk nanobubbles. To do this, glass nanopores are used as Coulter counters in order to detect nanobubbles. During ultrasonication, these transient bulk nanobubbles are shown to exist in relatively high concentrations while bubble activity on the surface of a solid media close to the pore is driven by ultrasound. However, the transient nature of these bubbles is evident upon termination of the ultrasonic source. Highspeed imaging suggests that these transient nanobubbles originate from the fragmentation of larger bubbles, which skate over the surface of the structure in the acoustic field present. Transient nanobubbles as small as ~100 nm diameter are detected. In contrast to previous work with microbubbles, no evidence for the oscillation of these nanobubbles during translocation was found. The novel experimental approach presented here provides strong evidence for the existence of transient nanobubbles in bulk solution.

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Yi-Lun Ying opened discussion of the introductory lecture by Justin Gooding: The nanointerface needs more comprehensive models to describe the interaction networks among water and ions. Would you please comment on how these models and understanding guide the applications of nanoelectrochemistry? Justin Gooding answered: This is a very difficult question which I don't think we know enough yet to give you a clear answer. What we do know is that with surfaces inside the substrate channels of our enzyme-like nanoparticles we have two to three layers of ice like water. Inside the channels that might mean that all the water is in an ice-like state. How this affects transport in the channel and the electrical double layer in electrochemical systems are big questions for us. Certainly, regarding transport, there is evidence for proton migration inside these channels and possibly sodium and potassium if they are present. But in our systems our materials are not well dened enough to tease out such effects. This was what my point was about regarding needing better dened materials to really understand the nature of the nanointerface in nanoparticle systems. There is however a lot of information we can extract from studies performed in the transport of species through nanochannels. I don't think we yet have an understanding though for case that I described where the nanochannels themselves are also reactive. 1,2

Yi-Tao Long opened a general discussion of the paper by Paul W. Bohn: The electrochemical nanoconnement makes a major impact on controlling the mass transport. Could you please comment on the multi-phase effects on the mass transport under nanoconnement. What's the next breakthrough application we could expected in controlling the mass transport in nanoconnement.