## 1 Introduction  
Sensor requirements include haptic sensibility, capability of sensing both shear stress and normal force for various sensing fields, sensing temperature, a strong and simple structure, softness, and large extension. Haptic sensors are commonly used in the field of robotics [1; 2; 3], and for sensing the surface roughness of various kinds of materials. Examples include tactile devices used in the machining of workpieces, sensing the roughness of human skin in the field of cosmetics, etc. In the former example, an apparatus that measures surface roughness using an extremely thin diamond needle that scratches the surface of the workpiece is ordinarily used. However, this apparatus requires a workpiece specimen cut from the precisely and mechanically processed surface of an automobile, airplane, ship, etc., to ensure stability on the measurement table. The use of such an apparatus damages the surface of the finished product. If a haptic sensor attached on a bar could be independently used as a part of the surface roughness measurement apparatus, it would protect the product. For example, [PERSON] devised a haptic sensor attached to the surface of a rubber fingersroughness. The stall could be fitted on a fingertip and then rubbed on the surface of the material being measured [4]. This technique is effective in precision machining. On the other hand, for skin-roughness measurement in the beauty industry, it is possible to obtain and evaluate, for example, the condition of skin after make-up removal, or the quality of human hair, as measurable numerical data. In addition, the technique is effective for the evaluation of the surface condition of materials such as sharkskin, and is applicable in the field of biotechnology for measuring surface roughness in paper, such as toilet paper, newspaper, and paper diapers [5]. With regard to robots, the inner mechanism of the robot is generally exposed or covered with a skin made of hard material, such as plastic or metal. Even if a rubber material is used, it will not possess haptic sensing like human skin. Therefore, force and thermal sensors must be installed in the material. In the future, it is likely that a skin for use in robots will be developed. Robot skin containing haptic sensors could be used to cover robots like human skin. We may come to have friendly feelings for robots once they begin to play an active part in our lives, as is imminent in terms of helping with household chores and nursing. Sensors are essential for sensing force and temperature in the inner mechanism of the robot. These correspond to the haptic sensing of human skin. The human skin has five types of touch sensation: tactile, baresthesia, alogometry, warm, and cold [6]. At present, robots can sense force and temperature with sensors to represent these five sense perceptions. An independent sensor is used for each. Therefore, many sensors are necessary, and the processing of the information they provide becomes complicated. The development of a simple sensor that handles information for multiple perceptions would be useful. Regarding this requirement, there has been typical and effective investigation of the capability of multi-signal acquisition in one sensor [7]. In addition, sensors are currently vulnerable to the characteristics of their materials, such as tensile and compression strength. A currently available robot sensor has unique sensitivity to a force applied normal to a touched material. When we need to measure the shear force on the robot, strain gauges or piezoelectric elements must be added [8; 9; 10; 11]. Thus, the sensor is complicated in structure and vulnerable to extrinsic mechanical forces. It therefore lacks extension, and is not suitable for applications where mimicking human skin is required. For a sensor to be useful in the skin of a robot, softness and large extension are important. Furthermore the cost of its production must allow mass production.