Microfluidic-Based Microinjectrode System for Combined Drug Infusion and Electrophysiology

Abstract

Source: Vanegas, M. I., et al. Microinjectrode System for Combined Drug Infusion and Electrophysiology. J. Vis. Exp. (2019)

This video demonstrates a microelectrode-based microfluidic device that delivers drug solution through a capillary tube, using an oil-based marker solution for precise volume tracking and enabling simultaneous neural recording and drug infusion.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Construction of the Microinjectrode for Stimulation and Recording (Figure 1a)

1. Measure the length of the cannula and the probe (in this example, a nanosensor). The probe must be longer than the cannula by the length it is to protrude from the cannula tip (depending on the probe design), plus approximately 2 cm.
2. Under a magnifier or a microscope (~10x magnification), load the probe into the cannula; if possible a back-loading is preferable to protect the tip of the probe.
   NOTE: This....

Results

Figure 1: Step by step fabrication of microinjectrode. (a) Configuration f.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3-port manual valves	LabSmith	Manual 3-Port Selector Valve (MV201-C360)	https://products.labsmith.com/mv201-manual-3-port-selector-valve/#.XNYEC9NKh26
Cannulae	Vita Needle Company	304 Stainless steel tubing, Outer Diameter 228μm, Inner Diameter 165μm	https://www.vitaneedle.com/assets/files/Vita_Needle_Master_Tubing_Gauge_Chart.pdf
Cleaving stone	Molex	Cleaving stone 1" x 1" (part No. 1068680064)	Highly recommended to follow method for cleaving capillary tubing: https://www.cmscientific.com/info_sheets/cleaving_procedure.pdf
Clorhexidine diacetate	Walmart	Nolvasan solution disinfectant (AAP311)	Used for microfluidic circuit flushing, dissolved at 20 g/L
Custom adapter	Custom provider	-	Custom machined adapter to connect microinjectrode to hydraulic microdrive
Driver	LabSmith	T7 TORX driver for installing breadboard screws (LS-TORX Driver)	https://products.labsmith.com/ls-torx-driver/#.XO8sndNKh25
Epoxy glue	LabSmith	Two-part high-strength epoxy adhesive (LS-EPOXY) for metal and plastic bonding	https://products.labsmith.com/ls-epoxy-12ml-epoxy-adhesive/#.XO8t89NKh24
Ferrule	LabSmith	One-Piece Fitting (C360-100) for connecting capillary, thru hole sized for 360μm OD capillary	https://products.labsmith.com/one-piece-fitting#.XNYEaNNKh24
Ferrule plug	LabSmith	One-Piece Plug (C360-101) for use in any -C360 port	https://products.labsmith.com/one-piece-fitting-plug/#.XNYFl9NKh24
Ferrule wrench	LabSmith	1/8" hex wrench for installing one-piece fittings and plugs (LS-HEX 1/8" Hex Wrench)	https://products.labsmith.com/ls-hex-1-8-hex-wrench/#.XO8sqtNKh24
Gastight syringe	Hamilton Company	500μL gastight syringe model 1750 (81220) and 1mL gastight syringe model 1001 (81320)	https://www.hamiltoncompany.com/laboratory-products/syringes/81220#top
Gold pins	Aim-Cambridge	Male gold plated crimp-on connector pin (40-9856M)	https://www.masterelectronics.com/aim-cambridge-cinch-connectivity-solutions/409856m-10109145.html
Lint-free wipes	Kimberly Clark	Kimtech Science Kimwipes Delicate Task	Lint-free wipes, used to identify leaks in the system
Liquid food color	McCormick & Co.	Water based, black liquid food color (52100581873)	https://www.mccormick.com/spices-and-flavors/extracts-and-food-colors/food-colors/black-food-color
Low viscosity oil	Clearco Products Co.	Pure Silicone Fluid Octamethyltrisiloxane with a viscosity of 1cSt at 25°C (PSF-1cSt)	http://www.clearcoproducts.com/pure-silicone-super-low-viscosity.html
Luer-Lock connector	LabSmith	Luer-Lock Adapter (C360-300), female fitting for connecting Luer Lock syringe to 360μm capillary tubing	https://products.labsmith.com/luer-lock-adapter-assembly#.XO81MtNKh24
Micro drill bits	Grainger	Micro drill bit, 0.23mm (414H85)	https://www.grainger.com/category/machining/drilling-and-holemaking/drill-bits/machining-drill-bits/micro-drill-bits
Microelectrode	FHC	Metal microelectrode, tungsten with epoxy insulation	https://www.fh-co.com/category/metal-microelectrodes
Oil hydraulic micromanipulator	Narishige Group	Oil Hydraulic Micromanipulator with guide tube attached (MO-96)	http://products.narishige-group.com/group1/MO-96/chronic/english.html
Polymicro Capillary Tubing	Molex	Polymicro Flexible Fused Silica Capillary Tubing (TSP150375), Outer Diameter 375µm, Inner Diameter 150µm	https://www.molex.com/webdocs/datasheets/pdf/en-us/1068150024_CAPILLARY_TUBING.pdf
Programmable syringe pump	Harvard Apparatus	Standard Infuse/Withdraw Pump, programmable (70-2213)	https://www.harvardapparatus.com/standard-infuse-withdraw-pump-11-pico-plus-elite-programmable-syringe-pump.html
Ruler	Empire	Stainless steel 6" Stiff ruler (27303)	http://www.empirelevel.com/rulers.php
Screw set	LabSmith	Valve mounting screw set (LS-SCREWS .25), thread-forming screws (2-28 x 1/4”) to mount valves to breadboard	https://products.labsmith.com/ls-screws-25#.XO8widNKh24
Standard Breadboard	LabSmith	4" x 6" platform (LS600), with 0.25" hole spacing for mounting fluid circuit	https://products.labsmith.com/standard-breadboard/#.XO8xDdNKh24
Sterile saline (sodium chloride) 0.9%.	Baxter	0.9% Sodium Chloride sterile	Sterile Intravenous Infusion
Sterile syringe filters	Millipore Sigma	MilliporeSigma™ Millex™-GP Sterile Syringe Filters with PES Membrane (SLGPM33RS)	https://www.fishersci.com/shop/products/emd-millipore-millex-sterile-syringe-filters-pes-membrane-green-4/slgpm33rs
Stoelting manual microsyringe pump	Stoelting Company	Manual infusion/withdrawal pump (51222)	https://www.stoeltingco.com/manual-infusion-withdrawal-pump-2649.html
T-junction	LabSmith	Interconnect tee (C360-203) for combining flow streams, for use with 360μm OD capillary tubing	https://products.labsmith.com/interconnect-tee#.XO8z8dNKh24