The biophysics of photothermal treatments with lasers and intense pulsed light systems

2021 ◽  
Vol 10 (Sup2) ◽  
pp. 40-43
Author(s):  
Mike Murphy
Keyword(s):  
Clinical Outcomes ◽  
High Energy ◽  
Intense Pulsed Light ◽  
Pulsed Light ◽  
Energy Devices ◽  
Good Grasp

Lasers and intense pulsed lights are commonly used for many skin applications today. An understanding of the basic biophysics is essential to achieve good clinical outcomes. Yet, the author's training experiences demonstrate that many users do not have a good grasp of some of these concepts. In this article, Mike Murphy will address these issues, and the most important parameters that need to be considered when treating the skin with high-energy devices will be identified

The Coupling Between Densification and Optical Heating in Intense Pulsed Light Sintering of Silver Nanoparticles

2016 ◽  
Author(s):  
Shalu Bansal ◽  
Chih-Hung Chang ◽  
Rajiv Malhotra
Keyword(s):  
Metallic Nanoparticles ◽  
High Speed ◽  
Flexible Substrate ◽  
High Energy ◽  
Intense Pulsed Light ◽  
Xenon Lamp ◽  
Pulsed Light ◽  
Ambient Conditions ◽  
Nanoparticle Deposition ◽  
Thermal Sintering

Sintering of nanoparticles deposited onto rigid or flexible substrate is required for many devices that use continuous and patterned thin films. An emerging need in this area is to perform nanoparticle sintering under ambient conditions, at high speeds, and with throughput that is compatible with high speed nanoparticle deposition techniques. Intense Pulsed Light sintering (IPL) uses a high energy, broad area and broad spectrum beam of xenon lamp light to sinter metallic and non-metallic nanoparticles. The capability of IPL to meet the above needs has been demonstrated. This paper experimentally examines temperature evolution and densification during IPL. It is shown, for the first time, that temperature rise and densification in IPL are related to each other. A coupled optical-thermal-sintering model on the nanoscale is developed, to understand this phenomenon. This model is used to show that the change in nanoscale shape of the nanoparticle ensemble due to sintering, reduces the optically induced heating as the densification proceeds, which provides a better explanation of experimental observations as compared to current models of IPL. The implications of this new understanding on the performance of IPL are also discussed.

Effect of Size Distribution on Optical Absorption During Intense Pulsed Light Sintering of Metal Nanoparticles

2018 ◽  
Author(s):  
Harish Devaraj ◽  
Hyun-Jun Hwang ◽  
Rajiv Malhotra
Keyword(s):  
Optical Absorption ◽  
Metal Nanoparticles ◽  
Size Distribution ◽  
Metallic Nanoparticles ◽  
Bimodal Distribution ◽  
High Energy ◽  
Intense Pulsed Light ◽  
Nanoparticle Size ◽  
Xenon Lamp ◽  
Pulsed Light

Intense pulsed light sintering (IPL) of nanoparticles on rigid or flexible substrates enables rapid fabrication of thin films and patterns over large areas. In IPL, visible light from a high energy xenon lamp is absorbed by the nanoparticles for rapid sintering of metallic and non-metallic nanoparticles. This plasmonic optical absorption during the process for metal nanoparticles has been shown to depend on individual nanoparticle size. However, but there is little understanding of how this absorption depends on nanoparticle size distribution during IPL. This work incorporates a fully three-dimensional packing model along with an electromagnetic model of plasmonic absorption in silver nanoparticles to bridge this gap. It is shown that smaller standard deviation in a unimodal distribution and smaller size ratios in a bimodal distribution demonstrate relatively higher optical absorption in IPL.

scholarly journals Decontamination of Powdery Foods Using an Intense Pulsed Light (IPL) Device for Practical Application

2021 ◽  
Vol 11 (4) ◽  
pp. 1518
Author(s):  
Hee-Jeong Hwang ◽  
So-Yoon Yee ◽  
Myong-Soo Chung
Keyword(s):  
Total Energy ◽  
Water Activity ◽  
Treatment Time ◽  
Sesame Seed ◽  
Pilot Scale ◽  
Black Pepper ◽  
Intense Pulsed Light ◽  
Pulsed Light ◽  
Energy Fluence ◽  
Color Changes

Controlling microbial problems when processing seeds and powdered foods is difficult due to their low water activity, irregular surfaces, and opaqueness. Moreover, existing thermal processing can readily cause various undesirable changes in sensory properties. Intense pulsed light (IPL) can be effective in nonthermal processing, and so two xenon lamps were attached to the sides of a self-designed cyclone type of pilot-scale IPL device. Each lamp was connected to its own power supply, and the following treatment conditions were applied to four sample types: lamp DC voltage of 1800–4200 V, pulse width of 0.5–1.0 ms, frequency of 2 Hz, and treatment time of 1–5 min. This device achieved reductions of 0.45, 0.66, and 0.88 log CFU/mL for ground black pepper, red pepper, and embryo buds of rice, respectively, under a total energy fluence of 12.31 J/cm2. Meanwhile, >3-log reductions were achieved for sesame seed samples under a total energy fluence of 11.26 J/cm2. In addition, analyses of color changes, water activity, and moisture content revealed no significant differences between the control and IPL-treated samples. These findings indicate that IPL treatment may be considered a feasible sterilization method for seeds and powdered foods.

Sign in / Sign up

Export Citation Format

Share Document