This paper presents current research on a miniaturized neuroprosthesis suitable for implantation into the brain. The prosthesis is a heterogeneous integration of a 100-element microelectromechanical system (MEMS) electrode array, front-end complementary metal-oxide-semiconductor (CMOS) integrated circuit for neural signal preamplification, filtering, multiplexing and analog-to-digital conversion, and a second CMOS integrated circuit for wireless transmission of neural data and conditioning of wireless power. The prosthesis is intended for applications where neural signals are processed and decoded to permit the control of artificial or paralyzed limbs. This research, if successful, will allow implantation of the electronics into the brain, or subcutaneously on the skull, and eliminate all external signal and power wiring. The neuroprosthetic system design has strict size and power constraints with each of the front-end preamplifier channels fitting within the 400 x 400-microm pitch of the 100-element MEMS electrode array and power dissipation resulting in less than a 1 degree C temperature rise for the surrounding brain tissue. We describe the measured performance of initial micropower low-noise CMOS preamplifiers for the neuroprosthetic.

The effect of alloy composition on the microstructure and mechanical behavior of four spray-deposited Al-Cu-Mg(-Ag-Mn) alloys was investigated. Precipitation kinetics for the alloys was determined using differential scanning calorimetry (DSC) and artificial aging studies coupled with transmission electron microscopy (TEM) analysis. DSC/TEM analysis revealed that the spray-deposited alloys displayed similar precipitation behavior to that found in previously published studies on ingot alloys, with the Ag containing alloys exhibiting the presence of two peaks corresponding to precipitation of both ⍀-Al 2 Cu and Ј-Al 2 Cu and the Ag-free alloy exhibiting only one peak for precipitation of Ј. The TEM analysis of each of the Ag-containing alloys revealed increasing amounts of Al 20 Mn 3 Cu 2 with increasing Mn. In the peak and over-aged conditions, Ag-containing alloys revealed the presence of ⍀ , with some precipitation of Ј for alloys 248 and 251. Tensile tests on each of the alloys in the peak-aged and overaged (1000 hours at 160 ЊC) conditions were performed at both room and elevated temperatures. These tests revealed that the peak-aged alloys exhibited relatively high stability up to 160 ЊC, with greater reductions in strength being observed at 200 ЊC (especially for the high Mn, low Cu/ Mg ratio (6.7) alloy 251). The greatest stability of tensile strength following extended exposure at 160 ЊC was exhibited by the high Cu/Mg ratio (14) alloy 248, which revealed reductions in yield strength of about 2.5 pct, with respect to the peak-aged condition, for the alloys tested at both room temperature and 160 ЊC.

No abstract

No abstract

No abstract