DEVELOPMENT OF A CHESS BOARD WITH SELF-POWERED MOVE RECOGNITION

Triboelectric nanogenerators (TENGs) have emerged as a possible solution to many problems of our modern world by satisfying the need for self-powered sensors and new methods of energy harvesting. One of the applications of TENGs as self-powered sensors is as pressure sensors. This can be done by making a TENG with only one electrode connected to a dielectric. This paper proposes a method of using TENG-based Kapton pressure sensors in order to make a self-powered chess board with move recognition capabilities. It was found that the voltage generated by the sensor at contact increased with increasing the placing force of a wooden cube (simulating a chess piece) on it. However, the voltage generated at separation did not increase with the placing force. It was also found that voltage always increased with the resistance between the electrode and the ground in a resistance range of 0.33 MΩ to 50 MΩ. Current usually increased with resistance at first then stabilized at some point. A chess board column was then created using 8 pressure sensors connected to each other via resistances. It was found that the voltage between the chess board column and the ground decreased as the square number on which the wooden cube was placed or removed from increased. Showing that this is a viable method of monitoring movements across this column.


INTRODUCTION
It is well known that when two materials come into contact with one another.A certain amount of charges are transferred between the two materials.This effect is known as the triboelectric effect or triboelectrification, [1,2].The amount and sign of the charges transferred to each surface can be determined via the triboelectric series [3,4].The lower a material is in the triboelectric series, the more likely it is to gain electrons when it comes into contact with another material.Kapton is a material that is generally known to be near the bottom of the triboelectric series, [5].
Ever since the era of IoT began, the need for self-powered sensors and energy harvesting has been evident.One of the inventions that have emerged in the past years that aims at fulfilling this need is the triboelectric nanogenerator (TENG) which uses the triboelectric effect in conjunction with electrostatic induction in order to generate power [6].TENGs can have multiple structure types, such as the contact-separation mode TENG, [7,8], sliding mode TENG, [9 -12], single-electrode TENG, [13 -16], and freestanding mode TENG, [17 -19].The contact-separation mode TENG can have either the two of its triboelectric layers with an electrode or it can have an electrode on one of its triboelectric layers which is connected to an electrical ground, [20].This second type can enable for the creation of pressure sensors.
Chess is one of the oldest games that is still popular in today's world.It consists of a board with 64 squares.16 pieces are controlled by each player and are placed at the ends of the board.Nowadays, even though the game is still played on a physical board for the most part.International chess tournaments usually keep an electronic record of all matches.Thus, chess boards with move recognition would be very useful in digitizing these games.This can be done by placing pressure sensors at each of the 64 squares of the chess board or by using computer vision, [21 -23].This paper proposes a method for monitoring movements on a chess board via TENG-based Kapton pressure sensors placed at the squares of the chess board.EXPERIMENTAL A TENG-based pressure sensor was made using Kapton as a triboelectric layer and aluminum foil as an electrode.The Kapton and aluminum foil layers were then pressed on a layer of 800 grit sandpaper.This layer was added in order to provide the Kapton layer with a lot of peaks and valleys on its surface and thus increasing the charge transfer between it and any other surface it touches, [24].The sensor was 60 mm × 60 mm.The object to be placed on the pressure sensor was a 20 mm × 20 mm × 20 mm wooden cube which was meant to simulate a wooden chess piece.The current generated by the pressure sensor was then fed to an electrical ground through a resistor or the circuit was left open.The voltage across that resistor was measured using an Arduino Uno.An illustration of this setup is shown in Fig. 1   The results of the measurement of the voltage output of the chess board column when the wooden cube was placed and removed from each square are shown in Fig. 10.It can be seen that in both cases, the voltage output of each square is less than that of the square before it.Going from about 0.16 to 0.095 volts in the case of contact and from about -0.125 to -0.058 volts in the case of separation.This indicates that this method could be utilized in order to find out which square a specific chess piece moved from and which square it moved to along the column based on the output voltage of the column.

CONCLUSIONS 1.
When the wooden block was placed on the pressure sensor at different placing forces, the voltage increased with the force only in the contact measurements.They stayed the same in the case of separation.

2.
In the tested resistance range, voltage always increased with increasing the external resistance.While current usually stabilized at a certain point.

3.
The voltage output of the tested chess board square was always lower than the square before it.

4.
The difference in voltage output between each square in the column in contact and separation shows that this method can be used to detect chess movements on the column.

Fig. 8 Fig. 9 Fig. 10 Fig. 5 Figures 6 Fig. 8 and 9
Fig. 8 Effect of the external resistance on the voltage and current output of the sensor at separation.