## 1 Introduction  
We conducted sequential studies that led to the novel method of production of sensors made from soft rubber that was developed for artificial skin, which is expected to be required as a substitute for human or robot skin, such as hybrid skin (H-skin) [1; 2; 3; 4; 5; 6; 7; 8; 9]. Through electrolytic polymerization, rubbers with C=C bonds, such as natural rubber latex (NR-latex), are capable of cross-linking molecules adequately to be solidified in themselves. This novel solidification method is different from the usual vulcanization technique where sulfur is used at the field for the ordinary production of solid rubber. Via electrolytic polymerization, we compound a magnetic responsive liquid, i.e., magnetic compound fluid (MCF), which has nm-ordered magnetite (Fe\({}_{3}\)O\({}_{4}\)) particles that are obtained by using a magnetic fluid (MF) during compounding and has um-ordered metal particles such as Fe,Ni, etc. By the application of a magnetic field on the compounded liquids with NR-latex and MCF during electrolytic polymerization, the magnetic particles are fabricated as heterostructures as many thin-rod shaped clusters that can be observed in organic thin film solar cells. Therefore, the electric and photovoltaic properties are enhanced, and the mechanical properties become anisotropic as well. Therefore, we named the electrolytically polymerized MCF rubber as H-Skin [7; 8; 9]. By doping the MCF rubber using any dopant, the electric and photovoltaic properties change as shown in Table 11 of the Appendix A. As diene-based rubbers involving isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR), nitrile rubber (NBR) or styrene-butadiene rubber (SBR) also have C=C bonds, they can be electrolytically polymerized. However, their Mooney viscosity must be so small such that they may be easily compounded into the MCF by adjusting the concentration of the rubber molecules. In the present study, we use NR-latex and CR-latex. Our previous investigations have focused on the body of the sensor, but not on the fabrication of electrodes attached to the rubber. The effect of the electrode fabrication on the characteristics of the electrolytically polymerized MCF rubber should be investigated. In general, the contact resistance between the electrodes and rubber is considerably large to become an issue [10]. Moreover, with respect to the MCF rubber, the contact resistance must be reduced such that the adhesion between the electrodes and MCF rubber has higher sensitivity. This problem is related to the general research themes of adhesion between the metal and rubber [11; 12; 13; 14; 15; 16; 17] and the prevention of corrosion of the metal surface [18; 19; 20; 21]. Hence, various methods of adhesion between the metal and rubber have been hitherto proposed. For example, a typical technique is the development of rubber or adhesive, involving conductive adhesives [22; 23]. On the other hand, dimethylpolysiloxane (PDMS) is one of conventional soft material. There have being investigations on the bonding between PDMS and metallic or non-metallic material related to patterning with gold for a soft sensor [24]. PDMS is suitable for micro-fluidic system applications and because of transparency. PDMS generally takes on silicone oil with liquid state and the silicone oil rubber is produced with using resin to PDMS. As the silicone oil rubber is one of non-diene-based rubber without double bond C=C, PDMS may be a conventional material to produce a non-diene rubber. In contrast, the diene-based rubber involving NR, CR et al. can have many hybrid properties by conductive, photovoltaic et al. effects because it has double bond C=C. The use of the diene-based rubber such as the present MCF rubber is suitable for the purpose of rendering the rubber sensory. Therefore, in the present report, we investigate the bonding between diene rubber and metallic material. In the present study, we propose a novel method for adhesion between the electrodes and MCF rubber by using metallic or non-metallic hydrous oxide.