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Title: Design and testing of microfabricated surgical tools for large animal probe insertion

Neural probes provide therapeutic stimulation for neuropsychiatric disorders or record neural activity to investigate the workings of the brain. Researchers utilize 6 mm long temporary silicon stiffeners attached with biodissolvable adhesive to insert flexible neural probes into rat brains, but increasing the probe length fivefold makes inserting large animal probes a significant challenge because of an increased potential for buckling. This study compared the insertion success rates of 6 mm and 30 mm long silicon stiffeners that were 80 μm wide and 30 μm thick, and ascertained the material thickness and modulus of elasticity that would provide successful insertion for a 30 mm probe. Using a microdrive, stiffeners were inserted into an agarose brain phantom at controlled insertion speeds while being video-recorded. Twenty-five percent of the 30 mm silicon stiffeners fully inserted at speeds approximately four times higher than the target rate of 0.13 mm/s, while 100 percent of the 6 mm silicon stiffeners inserted successfully at target speed. Critical buckling loads (Pcr) were calculated for the 6 mm and 30 mm silicon stiffeners, and for 30 mm diamond and tungsten stiffeners, with thicknesses varying from 30-80 μm. Increasing the thickness of the material by 10 μm, 20 μm andmore » 30 μm improved the Pcr by 2.4, 4.7 and 8.2 times, respectively, independent of the material, and substituting diamond for silicon multiplied the buckling capacity by 5.0 times. Stiffeners made of silicon for large animal probe insertion are not strong enough to withstand buckling upon insertion without a significant increase in thickness. Replacing silicon with diamond and increasing the thickness of the stiffener to 50 μm would afford a stiffener with the same Pcr capacity as the 6 mm silicon stiffener that had a 100 percent insertion success rate. Experiments should continue with diamond to determine a minimum thickness that will ensure successful insertions and provide an adequate margin of safety.« less
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Science Undergraduate Lab. Internship (SULI) Program
Country of Publication:
United States