In contrast to traditional passive probes comprising a limited number of recording sites (electrodes) positioned at fixed locations along the probe shaft, we also fabricate active probes. The shafts of these active probes are completely covered with hundreds of electrical switchable electrodes which are connected to an integrated switching matrix. This enables to reposition the electrode without mechanically repositioning the probe itself. The electrode position is virtually positioned by a mouse-click using the user-interface.
The active probe is called the electronic depth control (EDC) probe and contains 4 shafts with lengths of either 2 or 8 mm. The pitch between the shafts is 550 µm, the thickness of the probe is 50 µm. Each electrode, made of Iridiumoxide (IrOx), can be electrically connected to an output line. Each shaft contains 8 output lines which makes a total of 32 output channels per comb. The tip of the EDC shaft can also be equipped with the pointy-tip feature.
The 8 analog output lines per shaft are multiplexed and buffered using a custom Application Specific Integrated Circuit (ASIC) which is assembled onto the headstage or top part of the acute probe. A tether connects the signals to a control box which contains a modular data acquisition module.