Scaling limitations of silicon multichannel recording probes

The scaling limitations of multichannel recording probes fabricated for use in neurophysiology using silicon integrated circuit technologies are described. Scaled silicon probe substrates 8- mu m thick and 16- mu m wide can be fabricated using boron etch-stop techniques. Theoretical expressions for calculating the thickness and width of silicon substrates have been derived and agree closely with experimental results. The effects of scaling probe dimensions on its strength and stiffness are described. The probe shank dimensions can be designed to vary the strength and stiffness for different applications. The scaled silicon substrates have a fracture stress of about 2*10 ¹⁰ dyn/cm ², which is about six times that of bulk silicon, and are strong and very flexible. Scaling the feature sizes of recording electrode arrays down to 1 mu m is possible with less than 1% electrical crosstalk between channels.