Journal: Journal of neural engineering

Article Title: Neuromodulation Using Electroosmosis

doi: 10.1088/1741-2552/ac00d3

Figure Lengend Snippet: Set-up for measuring the injection volume of 1 mM glutamate against applied voltage pulses. A capillary attached to the top of the device was used to visualize displacement of the meniscus before and after glutamate injection for different voltages. A digital camera attached to a stereo microscope was used to image and track the meniscus. After lowering the micropipette tip into a Petri dish using a micromanipulator, a hold pressure was applied to prevent glutamate leakage through the micropipette tip. Once no leakage (meniscus movement) had been confirmed in the camera’s live feed, the device was supplied with voltage pulses. Voltage induced release of glutamate was confirmed by imaging the micropipette tip using epifluorescence microscopy (connected to an inverted microscope). Fluorescent particles dispersed in DI water flowed from the tip in concert with the applied voltage pulses.

Article Snippet: Since the inner diameter of the glass capillary is fixed, the total volume dispensed by the device was determined by measuring the meniscus displacement before and after 100 s. Images of meniscus displacement were captured using a 5 MP digital microscope camera (Moticam 5, Motic, Kowloon, Hong Kong) attached to a stereo microscope (SMZ 745T, Nikon, Tokyo, Japan) mounted on a boom stand and measured using image analysis software (Fiji, Schindelin et. al. [ ]).

Techniques: Injection, Microscopy, Imaging, Epifluorescence Microscopy, Inverted Microscopy

Journal: Journal of neural engineering

Article Title: Neuromodulation Using Electroosmosis

doi: 10.1088/1741-2552/ac00d3

Figure Lengend Snippet: A schematic showing the experimental set-up used for electroosmotic stimulation of the retina in-vitro. An explanted rat retina was placed onto a perforated microelectrode array pMEA), with the retinal ganglion cells (RGCs) contacting the electrodes of the pMEA. The retina’s health was sustained by perfusing it with oxygenated Ames medium, while maintaining perfusion from both top and bottom of the pMEA chamber. The glutamate filled electroosmotic flow (EOF) device was positioned using a micromanipulator (controlled by a stimulus computer) and the micropipette was interfaced with the retina while observing the tip-retina contact through an inverted microscope. When the contact was visually confirmed, the tip was lowered 40 μm further into the retina. Subsequently, retinal stimulations were achieved by EOF actuation of glutamate, generated by supplying voltage across the glass frit by two silver electrodes. The anode is connected to the positive voltage terminal on the sourcemeter, while the cathode is grounded. The stimulus computer was used to generate timed voltage signals with a set frequency, amplitude and number of stimuli. RGC spike data were obtained via the pMEA and the stimulus timings were recorded by a data acquisition computer.

Article Snippet: Since the inner diameter of the glass capillary is fixed, the total volume dispensed by the device was determined by measuring the meniscus displacement before and after 100 s. Images of meniscus displacement were captured using a 5 MP digital microscope camera (Moticam 5, Motic, Kowloon, Hong Kong) attached to a stereo microscope (SMZ 745T, Nikon, Tokyo, Japan) mounted on a boom stand and measured using image analysis software (Fiji, Schindelin et. al. [ ]).

Techniques: In Vitro, Microelectrode Array, Inverted Microscopy, Generated