**6. Conclusion**

As evident in this figure, with a higherfrequency, surface irregularities increase on the surface of the substrates. This enhances the surface topographic properties of the treated substrates

Furthermore, with a higher frequency, a larger amount of energy is delivered to the surface of the substrates, and the temperature increase causes more titanium oxide to form across the surface. This is similar to the results observed from the other parameters. Therefore, the substrates treated with a frequency of 100 kHz are expected to show the highest apatite‐

and therefore increases the biocompatibility of the titanium [25, 41–43].

**Figure 12** displays the EDX analysis of substrates immersed in SBF for 3 days.

**Figure 12.** Ti substrates soaked in SBF for 3 days (A) 25 kHz, (B) 50 kHz, (C) 100 kHz.

As evident in **Figure 12**, oxygen concentration slightly increases with an increase in frequen‐ cy, showing an increase in the concentration of titanium oxide. The higher oxidation level of titanium results in increased negative charge across the surface. Thus, positively charged CO2, Ca2+, NOx, and H2O atoms/ions are attracted to and absorbed by the negatively charged surface

as proteins. The attraction forces between the apatite and the negatively charged titanium oxides are increased through the laser treatment, which, in return, increases the biocompati‐

This can be further observed by looking at the SEM photography of substrates immersed in

In this figure, the apatite deposition layer is evident across the irradiated area. As observed from the EDX analysis, the apatite‐inducing ability of this substrate is high, which denotes the

), and create an environment with excellent affinity to biomaterials, such

inducing ability across their surface.

**5.1. Biocompatibility assessment**

368 370High Energy and Short Pulse Lasers

of the titanium (OH<sup>−</sup>

SBF.

bility of titanium [25, 42, 43].

**Figure 13** displays the result.

biocompatibility enhancement of the treated titanium.

In this chapter, a new method for micro/nano surface texturing of titanium was demonstrat‐ ed using nanosecond laser irradiation. The application of this method in bone and tissue implant fabrication was explored. Systematic experimental and theoretical studies on effects of the laser parameters on biocompatibility and bioactivity of titanium were conducted. The effects of each parameter were explored individually while other parameters were held constant. Predetermined patterns were induced across thin sheets of titanium substrates to investigate the effects of power, scanning speed, and frequency on surface of the substrates.

Microscopy analysis determined that an increase in power increases the surface topography and ablation across the surface of the material. However, increasing the power within the oxidation limit of titanium can lead to generation of titanium oxide along the irradiation area. Using SBF and cell adhesion, it was found that bioactivity of titanium increases in areas with higher surface topography and higher concentration of titanium oxide.

Additionally, scanning parameters, including pulse number and scanning speed, were found to be influential on the biocompatibility enhancement of titanium substrates. Through a series of experimental and theoretical analysis, it was concluded that a higher pulse numberincreases the surface energy of titanium substrates, and hence increases the biocompatibility along the irradiation area.

Finally, a range of frequencies was used to examine the bioactivity along the irradiation areas. Microscopy photographs displayed the generation of structures with higher surface topogra‐ phy along the laser‐induced patterns that have high oxidation and topography properties. Upon biocompatibility assessment, concentrations of calcium, oxygen, and phosphorous are observed on the surface, which shows the bioactivity enhancement of titanium.

This chapter introduced the use of commercially used nanosecond laser systems for biocom‐ patibility enhancement of titanium substrates for fabrication of bone and tissue implants. The key features of this method are described as following:


These key features make laser surface texturing desirable for rapid prototyping and fabrica‐ tion of biomedical devices, and can lead to improvements in cost and durability.
