75 research outputs found
Evaluation of transdermal drug delivery using terahertz pulsed imaging
Transdermal drug delivery (TDD) is widely used for painless dosing due to its minimally invasive nature compared to hypodermic needle injection and its avoidance of the gastrointestinal tract. However, the stratum corneum obstructs the permeation of drugs into skin. Microneedle and nanoneedle patches are ways to enhance this permeation. In this work, terahertz (THz) imaging is utilized to compare the efficacy of different TDD methods including topical application and via a needle patch. Our work shows the feasibility and potential of using THz imaging to quantify and evaluate different transdermal application methods
A robust protocol for in vivo THz skin measurements
This work presents an experimental setup to control the way in which pressure interferes with the repeatability of in vivo THz skin measurements. By integrating a pressure sensor circuit into our THz system, it is possible to identify which measurements were taken within a previously specified pressure range. The live response of the pressure sensor helps to acquire data within the desired pressure leading to greater consistency of data between measurements. Additionally, a protocol is proposed to help achieve repeatable results and to remove the effects of the natural variation of the skin through the course of the day. This technique has been shown to be able to quantify the changes induced in the skin following the application of a moisturising skin product and shows the measured result to be significantly different from natural skin variation. This research therefore prepares the way for further studies on the effectiveness of different skin products using in vivo THz measurements
THz sensing of human skin : a review of skin modeling approaches
The non-ionizing and non-invasive nature of THz radiation, combined with its high sensitivity to water, has made THz imaging and spectroscopy highly attractive for in vivo biomedical applications for many years. Among them, the skin is primarily investigated due to the short penetration depth of THz waves caused by the high attenuation by water in biological samples. However, a complete model of skin describing the THzāskin interaction is still needed. This is also fundamental to reveal the optical properties of the skin from the measured THz spectrum. It is crucial that the correct model is used, not just to ensure compatibility between different works, but more importantly to ensure the reliability of the data and conclusions. Therefore, in this review, we summarize the models applied to skin used in the THz regime, and we compare their adaptability, accuracy, and limitations. We show that most of the models attempt to extract the hydration profile inside the skin while there is also the anisotropic model that displays skin structural changes in the stratum corneum
Nonconsensual sharing of private sexually explicit media among university students
This research was the first in the U.K. to examine the prevalence and nature of non-consensual sharing of sexually explicit messages, pictures, and videos and to examine if this varies according to gender and by role (i.e. perpetrator, victim or as dual role of perpetrator/victim). In a sample of 391 young adults (aged 18-25 years) questionnaire data on subjective norms, consensual and non-consensual sharing, and their motivations for these behaviors were collected. Perpetration of and victimization through non-consensual sharing was experienced by a substantial number of individuals. There was an association between reporting perpetration of non-consensual sharing and experiencing victimization. An association was also found between reporting being pressured (i.e., coerced) to send sexually explicit material and experiencing victimization of non-consensual sharing, which suggests that these behaviours may form part of a continuum of violence and abuse, potentially within intimate relationships. No association was found between gender and (i) perpetration or (ii) victimization. However, from a gendered perspective, females perceived there was greater social pressure to post messages, pictures and videos, compared with males. Motivations for non-consensual sharing were commonly explained as for fun/a joke, and generally not thought of as problematic, although some victims perceived motivations to be more negative and/or related to revenge/causing distress. Given that this research examined non-consensual sharing across messages, pictures and videos for both victimization and perpetration and found it was both perpetrated and experienced by females and males, this does not support the common perception that this is a male perpetrated behaviour against women. This has implications for education, policy, intervention and prevention, with approaches needing to be inclusive of both males and females when addressing perpetration and victimization
Evaluation of in vivo THz sensing for assessing human skin hydration
Terahertz (THz) in vivo reflection imaging can be used to assess the water content of the surface of the skin. This study presents the results of treating 20 subjects with aqueous, anhydrous and water-oil emulsion samples and observing the changes induced in the skin using THz imaging. These regions were also measured with a corneometer, the present gold standard for skin hydration assessment within the cosmetics industry. We find that THz imaging is effective at observing the presence of oil and water on the surface of the skin, these results can be verified with the measurements of capacitance taken by the corneometer. The THz measurements reveal a distinction between the responses of subjects with initially dry or well hydrated skin, this observation is particularly noticeable with the oil-based samples. Additionally, moderate correlation was found between the THz reflected amplitude and capacitance of untreated skin with a correlation coefficient of r = -0.66, suggesting THz imaging has promising potential for assessing skin hydration
Real time THz imaging - opportunities and challenges for skin cancer detection
It was first suggested that terahertz imaging has the potential to detect skin cancer twenty years ago. Since then, THz instrumentation has improved significantly: real time broadband THz imaging is now possible and robust protocols for measuring living subjects have been developed. Here, we discuss the progress that has been made as well as highlight the remaining challenges for applying THz imaging to skin cancer detection
Optimized multilayer structure for sensitive THz characterization of thin-film glucose solutions
Terahertz time-domain spectroscopy (THz-TDS) has shown promise in biomedical sample characterization and high characterization sensitivity is in demand due to the thin-film (TF) feature of the sample. This paper proposes an optimized multilayer structure for sensitive characterization of TF aqueous solutions in reflection THz-TDS. Theoretical simulations are conducted for structural optimization and the 75 Āµm window-sample-mirror structure displays the best sensitivity compared to other sandwich structures and traditional THz measurement geometries. 0-20% TF glucose solutions are then measured; and a spectral peak introduced by the proposed structure is observed to result in the high sensitivity. Our work provides a new way of customizing multilayer structure for THz thin-film characterization
Monitoring the effect of transdermal drug delivery patches on the skin using Terahertz sensing
Water content of the skin is an important parameter for controlling the penetration rate of chemicals through the skin barrier; therefore, for transdermal patches designed for drug delivery to be successful, the effects of the patches on the water content of the skin must be understood. Terahertz (THz) spectroscopy is a technique which is being increasingly investigated for biomedical applications due to its high sensitivity to water content and non-ionizing nature. In this study, we used THz measurements of the skin (in vivo) to observe the effect of partially and fully occlusive skin patches on the THz response of the skin after the patches had been applied for 24 h. We were able to observe an increase in the water content of the skin following the application of the patches and to identify that the skin remained hyper-hydrated for four hours after the removal of the fully occlusive patches. Herein, we show that THz spectroscopy has potential for increasing the understanding of how transdermal patches affect the skin, how long the skin takes to recover following patch removal, and what implications these factors might have for how transdermal drug patches are designed and used
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