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Lasers in Medicine: Healing with Light
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
Similarly, tattoos can now be removed by using a variety of lasers whose wavelengths coincide with the absorption of the dyes used, while sparing surrounding skin. This is because many tattoo inks have broad absorption appreciable for wavelengths greater than 600 nm, where the absorption of hemoglobin and melanin has dropped off to relatively low levels. Pulsed lasers such as the Nd:YAG laser at 532 nm or the ruby laser at 694 nm can be used to fade blue and black tattoo pigments without scarring and bleaching the overlying skin (Figure 3.29). Inks that have absorption properties overlapping those of hemoglobin and melanin are harder to fade without skin damage. Melanin-pigmented blemishes such as café au lait spots, lentigos, or dark areas under the eye, can be bleached using wavelengths such as the argon ion 488 nm or ruby 694 nm light where melanin absorbs more strongly than hemoglobin.
Sustainable plant-based bioactive materials for functional printed textiles
Published in The Journal of The Textile Institute, 2021
Alka Madhukar Thakker, Danmei Sun
An apprehension was highlighted in this study wherein, synthetic tattoo inks for the protein nature of human skin are utilized to decorate the skin permanently with micro dermal injections of colors from pigments, dyes, and lake precipitates. Other synthetic additives such as diluters, pH controllers, thickeners, and stabilizers are auxiliary to tattoo ink mixture. The qualitative and quantitative assessment of chief trademark tattoo inks was conducted with Synchrotron radiation X-ray fluorescence spectroscopy, in concurrence with atomic absorption and Raman spectroscopy. The toxic metals and additives were detected in tattoo inks. Calcium, Ferrous, Copper, and Strontium were existing in all the testers. TiO2 was prominently present moreover as a transporter for dyes or as a pigment (Manso et al., 2019).
Graphene-based electrodes for ECG signal monitoring: Fabrication methodologies, challenges and future directions
Published in Cogent Engineering, 2023
Rimita Dey, Pravin Kumar Samanta, Ram Pramod Chokda, Bishnu Prasad De, Bhargav Appasani, Avireni Srinivasulu, Nsengiyumva Philibert
In 2017, Lu et al., (2017) invented a fully dry, “cut-and-paste”, time- and cost-effective technique for manufacturing epidermal electronics within a short period of time. They have reported about transparent, thin epidermal graphene electrodes, which can be attached directly to the epidermal layer of human skin temporarily like a tattoo and detect biopotential; it can generate ECG signal. The ECG signals detected by these electrodes can be comparable with the ECG signal detected by conventional wet electrodes. Researchers have used commercially available thin metalised polymer sheets in this method rather than following high vacuum metal deposition process. It shows 85% optical transparency, more than 40% stretchability and thickness of 463 ± 30 nm.
3D printing highly stretchable conductors for flexible electronics with low signal hysteresis
Published in Virtual and Physical Prototyping, 2022
Jun Zhou, Honghao Yan, Chengyun Wang, Huaqiang Gong, Qiuxiao Nie, Yu Long
In order to further study the influence of AA on the typical mechanical properties of elastomers, the representative stress–strain behaviour of PUA/IDA/AA-Elastomers with various AA content measured via tensile tests are presented in Figure 2(a,b), and summarised in Table S2, and our previous test data of PUA-20 was utilised as reference for comparison. It can be seen that the tensile fracture strain and elastic modulus of the measured PUA/IDA/AA-Elastomers can be significantly improved with the increase in AA content of the PUA/IDA/AA system. Compared with PUA-20, PUA-20-AA-5 exhibits a significant raise in the elongation at break from ∼260% to ∼400% and a gradual increase in elastic modulus from ∼0.13 to ∼0.22 MPa. When the weight percentage of AA in PUA/IDA/AA-Elastomers increased from 5 wt.% to 10wt.%, the elastic modulus of the elastomers ranged from 0.22 to 0.45 MPa, which is consistent with the foreseeable trend of the strength of hydrogen bonds, demonstrating that an increase in the degree of hydrogen bonding corresponded to a higher modulus. Many electronic devices (e.g. electronic skin, electronic tattoo) require that the elastic matrix have a modulus similar to that of human skin (∼0.15 to ∼0.25 MPa). Thus, it is a significant difference in modulus for these samples. It is also noted that the fracture strain had an impressive increase from ∼ 400% to ∼ 700%. It can be seen that the elastic modulus shows a gradual increase and the fracture strain raises greatly in this range (Figure 2(b)). In comparison, the elastic modulus showed a great increase but the fracture strain rises slightly when the AA continued to increase from 10wt.% to 15wt.%. The elastic modulus undergone an increase from ∼0.45 to ∼1.20 MPa, and the fracture strain increased from ∼700% to ∼810%.