## 1 Introduction  
Magnetic stimulation therapy has become a highly effective treatment for many neurological conditions, such as depression [1]. In 1985, Dr. [PERSON] invented transcranial magnetic stimulation, TMS, in which a current passes through a coil outside the head, with a strength of several kiloamps lasting a few hundred microseconds, and his device was able to stimulate the motor cortex in the brain [2]. This current causes a change in the magnetic field, which results in an induced electric field (electromagnetic induction) that can stimulate the nerves when it reaches the neuron's threshold for firing an action potential, helping and improving neurological symptoms such as depression and Alzheimer's disease [3; 4; 5]. Despite the widespread use of TMS therapy, it has poor spatial resolution, which makes it challenging to activate selectively the deeper targeted regions of the brain and achieve a focused stimulation [6; 7; 8; 9]. Recently, microcoil technology has been a significant development in magnetic stimulation therapy [10; 11; 12; 13; 14]. (The term \"microcoil\" is often used, although these devices do not necessarily have a circular shape like a traditional \"coil\" but rather sometimes appear to be more like a bent wire.) Unlike traditional TMS, microcoils induce a highly localized and precise electric field, making it easier to stimulate specific brain regions [15]. The improvement in spatial resolution comes at the cost of implanting the microcoil, which makes its use more invasive. Nevertheless, for some applications the increase in spatial resolution may override the disadvantage of implantation. Researchers have made considerable progress in constructing microcoils with various sizes, shapes, and configurations. In 2012, [PERSON] et al. designed a microcoil with a radius of 500 \(\upmu\)m and a height of 1 mm, made from 21 turns of copper wire placed 300 \(\upmu\)m above the soma of an isolated ganglion cell [6]. When a few amps of current were passed through this microcoil, it produced a strong enough electric field to stimulate neurons effectively. Since then, other researchers have designed different microcoils requiring several amps of current and multiple coil turns to stimulate neurons [16; 17]. This development of small, implantable microcoil technology has opened up new possibilities in treating neurological conditions, offering a new approach to magnetic stimulation therapy. The critical concept in understanding microcoil stimulation is the electric field that it can produce. It can be affected by multiple factors, including the strength of the current and its frequency, the distance between the coil and the nerves, the number of coil turns, and the properties of the surrounding tissues. In 2016, [PERSON] et al. designed a single-turn microcoil and they were able to stimulate neurons with only a 40 mA current. They claimed that magnetic stimulation was the mechanism of this excitation [18]. [PERSON] and [PERSON] were skeptical that magnetic stimulation was responsible for excitation because the induced electric field was too weak [19]. According to previous studies, the threshold for neuronal excitation is an electric field intensity of approximately 10 V/m [20,21]. (However, weaker fields, as low as 0.1 V/m, may alter the spontaneous firing rate in a neural network [22].) [PERSON] and [PERSON] suggested that capacitive coupling may be a more likely mechanism than magnetic stimulation [19]. The primary purpose of this investigation is to calculate the electric field in the brain during neural stimulation using capacitive coupling. This paper presents an analysis of the electric field induced by capacitive coupling by utilizing the parameters from [PERSON] et al. 's study [18]. We aim to provide a detailed calculation of the electric field generated by this method. Additionally, our study compares the results of the capacitive coupling analysis to the electric field expected during magnetic stimulation.