The relevant technology of Electronic skin (E-skin) is the current combination of electronics, machinery, medicine, materials, chemistry and other fields of technology research hotspot. Electronic skin can be applied to robots, human prostheses, VR virtual reality equipment, and wearable intelligent products, some scientists in the field of artificial electronic skin made significant progress in recent years.  As a result, we believe the progress of electronic skin related technology will bring revolutionary changes to the future of the world's life. Ruihu Tech  introduced electronic skin flexible tactile sensor, to achieve a low cost, high sensitivity, long life, consistency, and easy to produce.

Currently on the market of electronic skin is mainly divided into three categories:

First, the piezoelectric film. Many famous research and development staff more like the piezoelectric film type sensor, mainly because the piezoelectric resin has a uniform piezoelectric properties, dynamic stress sensitivity, and has good toughness and strong elasticity, size can be changed according to demand. The disadvantage is more expensive, cannot detect static force but transient.

Second, the varistor. There are many patents of varistor-type, as shown in Figure 1, a zigzag pattern, carbon nanotube film as a conductive layer, a certain degree of light transmission, the force to change the contact area of ​​the two conductive layer, change the resistance of the contact resistance.In addition, there are pressure-sensitive conductive rubber solution, most of the carbon nanotubes and graphene filled into the flexible substrate prepared by the piezoresistive sensor, regardless of the accuracy and cost of consumption has certain advantages and therefore preffered by the domestic researchers. The disadvantage is: their consistency is not good, the non-linear curve between pressure and resistance; between the two conductive layers need to maintain a certain distance, cannot rebound when using time is a little long.

Third, the capacitive type. Most of the latest research directions are using the capacitive, there is the high elastic colloid between the two conductive film, can also be filled with carbon black silicone rubber composite elastic medium.

                                 Figure 2

In theory, 

Where: ε0 is the dielectric constant of vacuum, εe is the effective dielectric constant of the composite dielectric, and its value is about the carbon black in the matrix. In the concentration of the function, A is the capacitive pressure sensitive unit plate equivalent area, d for the plate spacing. When the pressure sensitive unit is compressed, the plate spacing d decreases, the effective dielectric constant εe increases, making the output capacitance C increased, the synergistic effect of the two increases the sensitivity of the tactile sensor. The disadvantage is that capacitive with varistor as there is a non-linear problem, the detection circuit is more complex, there is also the problem of temperature drift.

Shenzhen Ruihu Technology Co., Ltd. is a local start-up company developing the electronic skin flexible touch sensor which principle is the strain gauges (Figure 3), different from the previous three types. It’s a pure detection of thin film deformation technology, the force change will lead to deformation of the film, the sensor will output linear voltage value according to bend deformation size. Figure 4 shows it has a very high strain coefficient, and strain range; can be bent to 10mm diameter circle with good flexibility.

                         Figure 3                                                                                                                             Figure 4

Ruihu Tech’s electronic skin is highly sensitive complex graphene material with the PET film surface coated, the thickness is only 0.3mm. In real applications, end customer needs add the rubber skin to both sides of Ruihu tech’s E-skin sensor, it also can works as a protective layer and flexibility body. When there is force change on the sensor, the rubber skin will be deformed, driving the sensing film deformation, so that the sensor output a different voltage. Figure 3, 3 for the rubber skin, 2 is the sensor film, 1 is a 3M adhesive foam adhesive.

                                                                                                  Figure 5

When sweeping robot wears the electronic skin of Ruihu Tech, it can better finish the sweeping process with automatic collision detection. In the walking robot project, the customer can put the E-skin sensor under the foot to detect of the ground is flat or not, so as to change the center of body gravity, to avoid robot dumping.

Ruihu’s electronic skin can also be used in the following areas with customer depth development cooperation n addition to the application of robot field.

1, automotive field, unmanned mode and manned mode switch detection. The lane hold function also needs to check if the steering wheel is held by the operator. Detection of driver driving or getting into sleepy by monitor the output of E-skin sensor attached on the steering wheel.

2, Healthy Activity: In the smart insoles, clothing, detect the force value under the foot of the runner, to guide the runner to correct the running posture reasonable to improve the training efficient and reduce the damage to the joints.

3, Smart home: used in tables and chairs, benches, for example to detect if someone sitting on a stool.

4, Production automation: in the mechanical arm grip strength testing to adaptively catch the cup, collision detection and quantity counting.

5, Intelligent traffic: traffic detection, traffic trigger, illegal parking and other applications.

6, Other: elevators, metro door closing detection sensors.

Ruihu Tech has owned a number of patents, can provide total solution including SOC chip and the detection module. Also provide PC debugging software tools, allowing users base on their application needs to make flexible configuration of the relevant functions and sensitivity.

Ruihu Tech launched electronic skin development hardware system and software development kit including a flexible touch sensor in Figure 6, a control panel development in Figure 7, PC software in Figure 8.

                                                                          Figure 6

                                                              Figure 7

                                                                          Figure 8

For more information and the Electronic Skin Development Kit, please visit www.ruihutech.com.

We welcome any cooperation to explore more new applications.