In order to solve the problems that the injury, hemorrhage, infection and edema of the brain tissue caused by brain electrodes implantation for aquatic animal robots, a light stimulation device and an optical control experiment method for carp robots are proposed in this paper. According to the shape of the carp skull, the device is a structure of Chinese character " 王” cut by a printed circuit board which can provide three groups of A, B and C bridge platforms for the light stimulation source. The two ends of a bridge in every group are welded with a jumper board, and the light emitting diodes (LED) are inserted into the jumper boards as the light stimulation source, and all negative poles of the jumper boards are connected to the console by the wire. A LED light can be replaced by another LED light according to the need of the wavelength of the LED light, and various combinations of the light stimulation modes can be also selected. This device was mounted on the carp robot’s head, the carp robot was placed in a water maze, and the optical control experiment method was observed to control the forward movement and steering movement of the carp robots (n = 10) under the dark light condition. The results showed that the success rates of the three groups of red light control experiments were 53%–87%, and the success rates of the three groups of blue light control experiments were 50%–80%. This study shows that the apparatus and the method are feasible.
To solve the problem of precise positioning of carp brain tissue coordinates, it is proposed in this paper for a method for transforming the coordinates of magnetic resonance imaging of carp brain tissue into the coordinates of electrode implantation using a brain stereotaxic apparatus. In this study, the 3.0T magnetic resonance imaging instrument was used to scan the carp brain. We independently established the three-dimensional positioning coordinate system of the brain, the three-dimensional coordinate assistance system of skull surface and the three-dimensional coordinate assistance system in brain tissue. After two coordinate transformations, the magnetic resonance image coordinates of the brain electrodes implantation sites were converted into the three-dimensional stereotactic coordinate system to guide the electrodes implantation. The experimental groups were divided into two groups, A and B. Group A was the group of magnetic resonance imaging apparatus combining with the brain stereotaxic apparatus, and group B was the group of brain atlas combining with the brain stereotaxic apparatus. Each group had 20 tails of carps (n = 20). This two methods were used to implant the electrodes into the cerebellar motor area. The underwater experiments of the carp robots were carried out to test the two methods. The results showed that the accuracy of the implanted electrodes were 90% in group A and 60% in group B. The success rate of group A was significantly higher than that of group B (P < 0.05). Therefore, the new method in this paper can accurately determine the coordinates of carp brain tissue.
As an interface between external electronic devices and internal neural nuclei, microelectrodes play an important role in many fields, such as animal robots, deep brain stimulation and neural prostheses. Aiming at the problem of high price and complicated fabrication process of microelectrode, a microelectrode twisting machine based on open source electronic prototyping platform (Arduino) and three-dimensional printing technology was proposed, and its microelectrode fabrication performance and neural stimulation performance were verified. The results show that during the fabrication of microelectrodes, the number of positive twisting turns of the electrode wire should generally be set to about 1.8 times of its length, and the number of reverse twisting rings is independent of the length, generally about 5. Moreover, compared with the traditional instrument, the device is not only inexpensive and simple to manufacture, but also has good expandability. It has a positive significance for both the personalization and popularization of microelectrode fabrication and the reduction of experimental cost.