Table 1.
Sample costs for 3-d printed parts.
Table 2.
Weights for 3-d printed parts.
Figure 1.
Measurements of electrode advance. advancement and retraction for printed and machined microdrive.
A 250 um glass electrode was loaded into the center position of the electrode grid. The drive was placed in rig that allowed us to measure the electrode travel as we turned the advancer. The electrode was advanced and retracted five times. Travel measurements were taken every 20 turns. Solid line shows data from the advancing phase and the dotted line shows data from the retracting phase for the printed (A) and machined version (B) of the microdrive. At the start of each cycle we realigned the electrode position to zero.
Figure 2.
Comparison of extracellular recording using PriED and a similarly designed professionally machined microdrive.
Recordings were made using 700–900 k FHC tungsten electrodes. (A) Sample recording using the stacked base design and using a cannula to pass the electrode through the dura to the anterior cingulate cortex of an awake NHP. (B) Sample recording using a professionally machined version of the microdrive recording from the basal forebrain in an awake NHP. Both panels show two excerpts from the recordings: 500 action potentials from the start of recording (near time 0s) and 500 action potentials from the end of the session (around 3500s). The insets show details of the recorded action potentials.
Figure 3.
Photos displaying both manual and motorized PriED configurations.
(A) Manual version with 3-d printed advancer. (B) Motorized version, showing stepper-motor, gear reduction box, and microcontroller. PriED is easily switched from manual to motorized configuration by removing the manual advancer and sleeve from the tower and sliding the motor in their place. The motor is then held in place by tightening the same set screw that formerly held the sleeve.
Figure 4.
Schematic of complete PriED assembly, showing stacked base on chamber with one tower attached.
(A) Top-down view of micro-drive highlighting the grid (1) and pad (2) where each tower attaches to the base. (B) Isometric view of the micro-drive. The sleeve (3), rails (4), notch that aligns with the grid (5), and set screw that attaches to the chamber (6). (C) Side-view highlighting the upper (7) and lower (8) base of the micro-drive when attached to the chamber (9). (D) Cut-away view showing tower (10), shuttle (11), lead screw (12), and upper adaptor (13).
Figure 5.
Schematics of single and stacked bases.
(A,B,C) Single piece base shown from top-down isometric, sectioned and bottom-up isometric views. Similarly for (D,E,F) for the stacked base.
Figure 6.
Schematic of electrode advancing tower assembly.
(A) Complete tower assembly showing detail of shuttle that carries the electrode. (B) Exploded view showing tower components. From top to bottom, an assembled tower consists of: sleeve, lower-adapter, motor holder, rails and lead-screw, shuttle, bearing and tower base. Not shown are the two 0–80 nuts that press fit into the shuttle. The sleeve and the bearing hold the lead-screw assembly in place, preventing it from sliding along the tower. The manual advancer (not shown) is keyed to mate with the lower-adapter and is used to turn it, thereby rotating the lead-screw.
Figure 7.
Schematic of stacked base with full complement of 10 towers.
(A) Bottom-up, (B) Side view and (C) cross-section views. All towers are independent and can be attached in any spatial arrangement as convenient for the experiment.
Table 3.
Bill-of-materials for off-the shelf metal parts.
Table 4.
Instructions to assemble a tower.
Figure 8.
(A) The electrode drive is shown with the single-piece base and three towers in the fully retracted position at the start of a recording session. The towers are carrying metal-in-glass electrodes that are positioned in three adjacent grid holes. The tower heights allow for 70 mm electrode travel which enables the towers to be used for deep brain recordings. The manual advancers are seen protruding from the tops of the towers.
Figure 9.
Stacked base and cannula system.
(A) The stacked base is printed as two parts. The lower base (electrode grid) attaches to the recording chamber and allows positioning of the cannula. The grid holes are 500 m in diameter to accommodate 26G cannuli. The upper base (adapter grid) recieves the towers, holds the electrode adapters and mates with the electrode grid after the cannuli are in place. (B) The cannula is cut from 26G TW (thin wall) tubing with 22G tubing as collar. The adapter is cut from 26G RW (regular wall) tubing. The slightly smaller inner diameter of the adapter compared with the cannula reduces the likelihood of electrode damage as the electrode is advanced.