**1.2.1 Experimental materials and media**

TiNi shape memory ally (SMA) (Ti: 49.3 at%, Ni: 50.7%) was used as the experimental material. A sample's size was 20mm×10mm×1mm. The TiNi SMA samples were ground by degrees with abrasive papers (No. W40-W10). After washed ultrasonically with absolute ethyl alcohol and acetone solutions, the samples were put in absolute ethyl alcohol to await for using.

The experimental media were the self-prepared Ti(SO4)2 solution (PH0.71) of 0.606mg/ml, Hank's solution (making up diluted hydrochloric acid and NaOH solutions into PH7.45) to simulate human body balanced salt solution, and simulated saliva[8] (making up lactic acid and ammonia water into PH6.13).

The method of self-preparation of Ti(SO4)2:

Weighing out 1.0108g of Titanium dioxide (99.9%) pre-burned at 800C for 2h, putting it in a platinum crucible with a platinum cover, adding to 3g of potassium pyrosulfate to melt, then putting it in a beaker of 400ml after taken out and cooled; adding sulphuric acid solution of 200ml, leaching the liquid melt at an electric heater, then taking the platinum crucible out and clearing with water, continuing to heat until to the solution clarify entirely, cooling, moving it into a volumetric flask of 1000ml, diluting to the graduation with deionized water, and finally, shaking the flask to be even, in order to get ready to use. And this Ti concentration was 0.06 mg/ml.

Hank's solution composition:

2 3 2 4 2 4 2 2 4 2 2 NaCl 8g/l + Na HCO 0.35g/l + Na HPO 0.0475g/l + KCl 0.4g/l +KH PO 0.06g/l + MgCl 6H O 0.10g/l + MgSO 7H O 0.10g/l + CaCl 0.18g/l + Glucose 1g/l.

Fusayama solution composition:

KCNS 0.52g/l + NaHCO 1.25g/l + KCl 1.47g/l + NaH PO 0.19 <sup>3</sup> 2 4 g/l + lactic acid 0.75ml.
