**3. Reduction of adhesion between steel and grilled fish protein with Ultra‐ Hydrophobic DLC**

When you grill fish, you probably have experiences that skin and meat of the fish has adhered to some metal grids. This issue is still unsolved on the adhesion of the denatured fish body by heating. Conventional grids of grill are coated with Fluorine resin to avoid the severe adhe‐ sion of grilled fish to the grids. If the maximum temperature of grilling room is less that 300 <sup>o</sup> C, the coatedgridwithFluorine resincanworkwell.Howeverwhenthe temperature inthegrilling room rises up to 500 <sup>o</sup> C, conventional grill rods with Fluorine resin coating can not work well, because Fluorine resin should disappear by heat decomposition. The recent grilling equip‐ ment heats both from top side and bottom side, and extra heating is applied to the grilling rods thatrise it up to 500 <sup>o</sup> C even if the temperature on contact part between grid and fish is at about 150 <sup>o</sup> C.

Therefore we have tried to develop new grills that have weak adhesion to grilled fish and temperature endurance at high temperature. We consider that the reason why Fluorine resin coating can reduce the adhesion is the Fluorine resin has low surface energy and hydopho‐ bicity. If we can introduce the new coating that has ultra‐hydrophobicity and temperature endurance up to 500 <sup>o</sup> C, it can work well. So we focused on Ultra‐Hydrophobic Diamond‐like Carbon coating named as UH‐DLC coating [7]. If it can keep the ultra‐hydrophobic properties up to the 500 <sup>o</sup> C, it has the possibility to use for the new grill rods.

(1)23 oC (2)100 oC, 9minutes (3)200 oC, 9 minutes

Tribology for Biological and Medical Applications 227

(4)300 oC, 9 minutes (5)400 oC, 9 minutes (6)500 oC, 9 minutes

Ultra‐Hydrophobic Diamond‐like Carbon were coated by surface wave‐excited plasma CVD that used Ar gas and TMS (Tetra Methyl silane, [Si(CH3)4]) gas as precursor gases on stainless steel block and grilling rods. Figure 7 shows the cross sectional SEM image of the UH‐DLC

Here we explain how to coat the UH‐DLC film. Figure 8 shows the schematic of the PECVD equipment with a stainless‐steel chamber that is 400 mm in inner diameter and 300 mm in height, presently employed for some grill rods. Figure 8 (b) shows a jig which keep grill rods parallel to the quartz tube. We set it on the insulator and attached some grill rods on its jigʹs 3.0 mm hole. And in case of block specimens, we only place them on the jig. Priorto deposition, gas pressure in the chamber was decreased to degrees of 10<sup>−</sup><sup>4</sup> Pa with turbo‐molecular pump. The bottom end of the chamber was connected to a coaxial waveguide through which 2.45‐ GHz microwaves were introduced via a quartz plate coupled with a quartz tube that is 20 mm

2.45‐GHz microwaves introduced into the chamber propagate as surface wave along the interface between the surface of quartz tube and plasmas, generating high‐density plasma column along the tube as shown in Figure 8. As precursor gases, CH4 and Tetra Methyl silane

For ultra‐hydrophobic structure of DLC coating on the sample surface, an azimuthally symmetric 2.45 GHz surface wave‐excited plasma (SWP) was proposed. When high working pressure at 220 Pa and TMS gas mixture, it has a profound effect on nanoscale post generation because of large TMS particle is flow inner chamber. And also etching with glow discharge of

At first, we observed the block specimen coated Ultra‐Hydrophobic Diamond‐like Carbon by SEM. And then we heated the flat specimen coated UH‐DLC in an electric furnace for 9 minutes

(TMS, Si (CH3)4 ) are introduced into the chamber together with Ar gas.

**Figure 9.** The status of UH-DLC film after heating at each temperature for 9 minutes

coatings of on specimen.

in diameter and 2 mm in thickness.

Ar gas was another effect of rough surface.

In this study, we introduced UH‐DLC coating to grill rods and evaluate the possibility of its usage. In order to know the temperature endurance of UH‐DLC coatings, we evaluated the effect of annealing temperature on the morphology and contact angle of water. Also we evaluated the effect of UH‐DLC coating on the adhesion of real fish after grilling [3].

**Figure 7.** FE-SEM image of the needle-like structure of UH-DLC surface

**Figure 8.** (a); The schematic of 2.45 GHz surface wave-excited plasma (SWP) apparatus, (b); Jig for grill rods

**Figure 9.** The status of UH-DLC film after heating at each temperature for 9 minutes

Therefore we have tried to develop new grills that have weak adhesion to grilled fish and temperature endurance at high temperature. We consider that the reason why Fluorine resin coating can reduce the adhesion is the Fluorine resin has low surface energy and hydopho‐ bicity. If we can introduce the new coating that has ultra‐hydrophobicity and temperature

Micro-Nano Mechatronics — New Trends in Material, Measurement, Control, Manufacturing and Their Applications in

Carbon coating named as UH‐DLC coating [7]. If it can keep the ultra‐hydrophobic properties

In this study, we introduced UH‐DLC coating to grill rods and evaluate the possibility of its usage. In order to know the temperature endurance of UH‐DLC coatings, we evaluated the effect of annealing temperature on the morphology and contact angle of water. Also we

C, it has the possibility to use for the new grill rods.

evaluated the effect of UH‐DLC coating on the adhesion of real fish after grilling [3].

**Figure 7.** FE-SEM image of the needle-like structure of UH-DLC surface

**Grill rod**

**(a)**

C, it can work well. So we focused on Ultra‐Hydrophobic Diamond‐like

2 m

3 22.5°

**(b) Jig for grill rods**

10

**Jig for grill rods**

**Figure 8.** (a); The schematic of 2.45 GHz surface wave-excited plasma (SWP) apparatus, (b); Jig for grill rods

endurance up to 500 <sup>o</sup>

Biomedical Engineering

226

up to the 500 <sup>o</sup>

Ultra‐Hydrophobic Diamond‐like Carbon were coated by surface wave‐excited plasma CVD that used Ar gas and TMS (Tetra Methyl silane, [Si(CH3)4]) gas as precursor gases on stainless steel block and grilling rods. Figure 7 shows the cross sectional SEM image of the UH‐DLC coatings of on specimen.

Here we explain how to coat the UH‐DLC film. Figure 8 shows the schematic of the PECVD equipment with a stainless‐steel chamber that is 400 mm in inner diameter and 300 mm in height, presently employed for some grill rods. Figure 8 (b) shows a jig which keep grill rods parallel to the quartz tube. We set it on the insulator and attached some grill rods on its jigʹs 3.0 mm hole. And in case of block specimens, we only place them on the jig. Priorto deposition, gas pressure in the chamber was decreased to degrees of 10<sup>−</sup><sup>4</sup> Pa with turbo‐molecular pump. The bottom end of the chamber was connected to a coaxial waveguide through which 2.45‐ GHz microwaves were introduced via a quartz plate coupled with a quartz tube that is 20 mm in diameter and 2 mm in thickness.

2.45‐GHz microwaves introduced into the chamber propagate as surface wave along the interface between the surface of quartz tube and plasmas, generating high‐density plasma column along the tube as shown in Figure 8. As precursor gases, CH4 and Tetra Methyl silane (TMS, Si (CH3)4 ) are introduced into the chamber together with Ar gas.

For ultra‐hydrophobic structure of DLC coating on the sample surface, an azimuthally symmetric 2.45 GHz surface wave‐excited plasma (SWP) was proposed. When high working pressure at 220 Pa and TMS gas mixture, it has a profound effect on nanoscale post generation because of large TMS particle is flow inner chamber. And also etching with glow discharge of Ar gas was another effect of rough surface.

At first, we observed the block specimen coated Ultra‐Hydrophobic Diamond‐like Carbon by SEM. And then we heated the flat specimen coated UH‐DLC in an electric furnace for 9 minutes

at 100 <sup>o</sup> C. After that, we observed UH‐DLC coating by SEM. Next, we heated this specimen which was heated at 100 <sup>o</sup> C in the electric furnace for 1 hour at 200 <sup>o</sup> C. The same as described above, we also heated at 300 <sup>o</sup> C, 400 <sup>o</sup> C, and 500 <sup>o</sup> C. And then observed its specimen by SEM after heating at each temperature. Figure 9 shows six SEM pictures of the UH‐DLC coating after heating in the electric furnace every for 9 minutes at each temperature. We could confirm that surface of the UH‐DLC coating looked a little rough as the heating with the rise of temperature, but this coating did not disappear and show big change.

that of no coating grills. Also it was confirmed that the adhesion force of the UH‐DLC coating

In this section, we proposed new grill rods that were coated with Ultra‐Hydrophobic Dia‐ mond‐like Carbon. The adhesion of grilled fish to Ultra Hydrophobic DLC coating grill rods were as half as that of no coating grill rods and as much as that of Fluorine resin coating grill rods. Moreover, Ultra Hydrophobic Diamond‐like Carbon has heat endurance at 500 <sup>o</sup>

grilling room. On the other hand, the hydrophobic property of Fluorine resin coating disap‐

Carbon coating has a possibility for the usage as new grilling grids at high temperature.

C of the grilling room. So, we believe that Ultra Hydrophobic Diamond‐like

Fish; horse mackerel Cooking time; 9 minutes Position; Center of grill In a grilling equipment

Grill specimen No coating UH-DLC Fluorine resin

**4. Increasing of bonding strength between probe DNA and polymer**

Mapping of all DNA sequence of human had finished by The International Human Genome Project in 2000. Thus difference of gene of each human can be measured. If distinctive sequence in DNA sequence of human having disease caused by gene can be found, observation of mechanism of such disease and development of new medicine moved ahead well. DNA chip is an apparatus to examine DNA, on which DNA is fixed. Existing DNA chip is "for research and development", and expensive. So, "for clinic", inexpensive, more reliable and sensitive

Therefore DNA chip made from a plastic was suggested [8]. For high reliability and sensitivity, affinity between DNA and plastic must be higher. But plastic is hydrophobic, affinity to DNA

C of

Tribology for Biological and Medical Applications 229

grill rods was as much as those of the Fluorine resin coating grill rods.

0

**Figure 11.** Experimental result of grilling fish in the gas grill equipment

DNA chip is needed as shown in Figure 12.

**substrate for DNA chip with ion beam irradiation**

1

2

3

4

0.5

1.5

Adhesion force *F*, N

2.5

3.5

peared at 500 <sup>o</sup>

**Figure 10.** (a) The exclusive jig for pulling fish, (b) The schematic of pulling a fish

In order to know the reduction effect of UH‐DLC and Fluorine coatings on adhesion of grilled fish against grilling rods, the adhesion was evaluated from the maximum pilling force of the fish after grilling with gas grill equipment.

We used an exclusive jig for pulling a fish as shown in Figure 10(a). We used a horse mackerel as standard fish, because a horse mackerel is one of the standard fish for the test. We put an exclusive jig and then a horse mackerel on the center of grids of grill as shown by Figure 10(b), and put them in the grilling equipment. We used only three grillrods forthis experiment as shown in Figure 10(b). We heat them for 9 minutes. While we heat them, we checked the temperatures with two thermocouples in the grill equipment. Certainly, we confirmed that the temperature in the grill equipment was about 500 <sup>o</sup> C and the contact temperature between fish and the grill rod was 150 <sup>o</sup> C. After that, we take them out from the grilling room, and leave them for 1 minute in air. And then we pull the fish up with a pulling gauge and measure the maximum adhesion force.

We did the adhesion test of a real fish in the grilling equipment for differentrods as no coating, UH‐DLC coating and Fluorine resin coating. Figure 11 shows the adhesion result of this experiment. These results were the average adhesion force of four time experiments. The adhesion forces of UH‐DLC coating and Fluorine resin coating grill rods were as about half as that of no coating grills. Also it was confirmed that the adhesion force of the UH‐DLC coating grill rods was as much as those of the Fluorine resin coating grill rods.

In this section, we proposed new grill rods that were coated with Ultra‐Hydrophobic Dia‐ mond‐like Carbon. The adhesion of grilled fish to Ultra Hydrophobic DLC coating grill rods were as half as that of no coating grill rods and as much as that of Fluorine resin coating grill rods. Moreover, Ultra Hydrophobic Diamond‐like Carbon has heat endurance at 500 <sup>o</sup> C of grilling room. On the other hand, the hydrophobic property of Fluorine resin coating disap‐ peared at 500 <sup>o</sup> C of the grilling room. So, we believe that Ultra Hydrophobic Diamond‐like Carbon coating has a possibility for the usage as new grilling grids at high temperature.

**Figure 11.** Experimental result of grilling fish in the gas grill equipment

at 100 <sup>o</sup>

228

which was heated at 100 <sup>o</sup>

Biomedical Engineering

above, we also heated at 300 <sup>o</sup>

C. After that, we observed UH‐DLC coating by SEM. Next, we heated this specimen

C. The same as described

C. And then observed its specimen by SEM

C and the contact temperature between fish

C. After that, we take them out from the grilling room, and leave

Pulling up

C in the electric furnace for 1 hour at 200 <sup>o</sup>

Micro-Nano Mechatronics — New Trends in Material, Measurement, Control, Manufacturing and Their Applications in

after heating at each temperature. Figure 9 shows six SEM pictures of the UH‐DLC coating after heating in the electric furnace every for 9 minutes at each temperature. We could confirm that surface of the UH‐DLC coating looked a little rough as the heating with the rise of

In order to know the reduction effect of UH‐DLC and Fluorine coatings on adhesion of grilled fish against grilling rods, the adhesion was evaluated from the maximum pilling force of the

We used an exclusive jig for pulling a fish as shown in Figure 10(a). We used a horse mackerel as standard fish, because a horse mackerel is one of the standard fish for the test. We put an exclusive jig and then a horse mackerel on the center of grids of grill as shown by Figure 10(b), and put them in the grilling equipment. We used only three grillrods forthis experiment as shown in Figure 10(b). We heat them for 9 minutes. While we heat them, we checked the temperatures with two thermocouples in the grill equipment. Certainly, we confirmed that the

them for 1 minute in air. And then we pull the fish up with a pulling gauge and measure the

We did the adhesion test of a real fish in the grilling equipment for differentrods as no coating, UH‐DLC coating and Fluorine resin coating. Figure 11 shows the adhesion result of this experiment. These results were the average adhesion force of four time experiments. The adhesion forces of UH‐DLC coating and Fluorine resin coating grill rods were as about half as

C, and 500 <sup>o</sup>

C, 400 <sup>o</sup>

temperature, but this coating did not disappear and show big change.

(a) (b)

**Figure 10.** (a) The exclusive jig for pulling fish, (b) The schematic of pulling a fish

fish after grilling with gas grill equipment.

temperature in the grill equipment was about 500 <sup>o</sup>

and the grill rod was 150 <sup>o</sup>

maximum adhesion force.
