Arduino based intra-cerebral microinjector device for neuroscience research

Abstract

Stereotaxic surgery is a less invasive form of surgery that uses a three-dimensional coordinate system to place instruments at a specific location in the brain. Through this type of surgery, one can place needles among other tools within the structures of the brain. Therefore, injections can be given in order to deliver substances that cannot cross the blood-brain barrier. The two most important parameters of the microinjection to control are volume and speed. The volume should not be so large that it displaces the brain tissue and tears it. The injection speed must also be slow so that the liquid that comes out of the syringe can diffuse into the tissue without displacing it and damaging it. Thus, the objectives of the present work are: 1) To develop not a 3D printed prototype but an end-user device. 2) The device must be for animal research only. 3) It must have the same precision in volume and speed as commercial devices. 4) It must be adjustable for microsyringes from 0.5 µl to 1 ml. 5) It must be possible to place it directly on the stereotaxic surgery apparatus and to use it separately. 6) The price must be substantially lower than that of the commercial devices.

Keywords: Arduino; Intracerebral injection; Microinjection; Neuroscience; Open hardware; Stereotaxic surgery.

Graphical abstract

Fig. 1

The different parts of the microinjector and their location.

Fig. 2

Assembly of the microinjector. A parts list for the microinjector and the first steps of assembly.

Fig. 3

Steps for assembly of the microinjector.

Fig. 4

Final steps for assembly of the microinjector.

Fig. 5

Steps for assembly of the microinjector controller.

Fig. 6

Steps for assembly of the scissor jack.

Fig. 7

Electronic circuit connections.

Fig. 8

Software menu screens. The stroke of the syringe is the distance measured in mm from zero volume to the maximum of the scale.

Fig. 9

28byj-48 motor specifications.

Fig. 10

Validation. A graph of ejected volume as a function of the selected volume. B graph of accuracy and variation coefficient.

Fig. 11

Design. A microinjector mounted on the stereotaxic surgery apparatus. B microinjector mounted on its scissor jack outside the stereotaxic surgery apparatus.

Fig. 12

Stereotaxic surgery. The animal is mounted on the apparatus and the lambda reference point is located, which is the point between the crossing of the sagittal and coronal suture. From this point on, the atlas of stereotaxic surgery maps all the structures of the brain in the three XYZ planes.

Fig. 13

Scientific Application of the microinjector. A The brain of the mouse during the slice. You can see the mark left by the injection of methyl violet without tissue damage. B cell transfected with viral vector containing a protein that fluoresces in the presence of intracellular calcium. C location of the mark left by methyl violet in the atlas of stereotaxic surgery. D Micrograph of the brain slice showing the methyl violet mark. No tissue damage noted. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)