Our drive implant design, the flexDrive just got published at Frontiers Systems Neuroscience:
Voigts J, Siegle JH, Pritchett DL and Moore CI (2013). The flexDrive: An ultra-light implant for optical control and highly parallel chronic recording of neuronal ensembles in freely moving mice. Front. Syst. Neurosci. 7:8. doi: 10.3389/fnsys.2013.00008 (link)
The implant design is a relatively basic iteration of the commonly used movable electrode bundle method, but presents a significant step towards making the implant smaller and lighter at about ~2g and increasing the number of simultaneously adjustable electrodes that can be placed to 16.