In Vivo Confocal Scanning Laser Microscopy of Human Skin: Melanin Provides Strong Contrast

Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, flexible, and stretchable electronic devices provide a novel platform to interface with soft tissues for robotic feedback and control, regenerative medicine, and continuous health monitoring. Here, we introduce the term “lab-on-skin” to describe a set of electronic devices that have physical properties, such as thickness, thermal mass, elastic modulus, and water-vapor permeability, which resemble those of the skin. These devices can conformally laminate on the epidermis to mitigate motion artifacts and mismatches in mechanical properties created by conventional, rigid electronics while simultaneously providing accurate, non-invasive, long-term, and continuous health monitoring. Recent progress in the design and fabrication of soft sensors with more advanced capabilities and enhanced reliability suggest an impending t...

Lab-on-Skin: A Review of Flexible and Stretchable Electronics for Wearable Health Monitoring

This report reviews individual-related variables, environment-related variables and instrument-related variables, with a focus on the Evaporimeter EP1 (ServoMed). Start-up and use is described, and guidelines for good laboratory practice given.

Guidelines for transepidermal water loss (TEWL) measurement. A report from the Standardization Group of the European Society of Contact Dermatitis.

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International commission on non-ionizing radiation protection.

In vivo confocal scanning laser microscopy of human skin II: advances in instrumentation and comparison with histology.

In vivo measurements taken by valid methods, help to interpret the phenomena associated with the aging process. The authors developed some routine techniques to measure physical properties of the skin both deep in the dermis-epidermis and at the surface (stratum corneum). Measurements on the forearm of 150 people yielded the following results regarding the dermis-epidermis level: (1) skin thickness begins to decrease at 45 years of age for men and women, when women's skin becomes thinner than men's skin; (2) torsion extensibility, normalized for a given skin thickness, sharply decreases after 35 years of age; (3) skin optical properties are modified, ie the photoplethysmographic signal, measured on the forehead, greatly increase after 60 years of age; (4) at the cutaneous surface level, the main modifications are increased shedding of stratum corneum after 60 years of age in parallel with a modification of the stratum corneum cohesivity, altered skin microrelief during the aging process, and slightly decreased transepidermal water loss while the corneocyte projected size increases. These findings allow consideration of the aging process at the skin level as a phased process. The alterations of the physical properties and their kinetics suggest a various process according to the different cutaneous sections.

In Vivo Studies of the Evolution of Physical Properties of the Human Skin with Age

The role of race in modulating skin responses has been investigated. Several parameters (skin thickness, transepidermal water loss, water content of the stratum corneum and skin biomechanics) have bee

In vivo Biophysical Characterization of Skin Physiological Differences in Races

This study sought to investigate whether cosmetics do improve female facial attractiveness, and to determine whether the contribution of different cosmetic products are separable, or whether they function synergistically to enhance female beauty. Ten volunteers were made up by a beautician under five cosmetics conditions: (i) no make-up; (ii) foundation only; (iii) eye make-up only; (iv) lip make-up only; and (v) full facial make-up. Male and female participants were asked to view the 10 sets of five photographs, and rank each set from most attractive to least attractive. As predicted, faces with full make-up were judged more attractive than the same faces with no make-up. Sex differences within the results were also apparent. Women judged eye make-up as contributing most to the attractiveness. Men rated eye make-up and foundation as having a significant impact on the attractiveness of a full facial makeover. Surprisingly, lipstick did not appear to contribute to attractiveness independently.

Do cosmetics enhance female Caucasian facial attractiveness

The response of the forearm skin to a 9  10(-3) N  m torque was measured on 141 subjects aged 3-89 years The results for each age class were adjusted to a skin thickness of 1 mm by use of a skinfold caliper Results indicate a maximum skin thickness around the age of 40 years Standardised skin extensibility decreases with age, the skin of females being less extensible than that of males These results, which should be considered in relation to the total water content of the skin, are compared to those of other papers dealing with this subject

Influence of ageing on the in vivo extensibility of human skin at a low stress.

Real-time confocal microscopy has brought substantial improvements to the imaging of the human skin in vivo. On early images, the stratum corneum could be distinguished from the living epidermis and the circulatory network of the superficial dermis. We have adapted the Tandem Scanning Microscope to obtain images of the living skin, showing thinner structures such as the stratum lucidum and the dermo-epidermal junction, both of which are essential markers for micron-order measurements of the thickness of the stratum corneum and living epidermis. The measurements were corrected for the differences in the refractive index of the various cutaneous layers, and the undulation of the dermo-epidermal junction. Furthermore, nucleus size and number could be assessed from horizontal optical sections. To illustrate the sensitivity of the thickness measurements, changes in the thickness of the epidermis were recorded during and after stripping of the horny layers. This non-invasive methodology is a very promising tool for morphometric studies of the living human skin at the cellular level.

J. L. Leveque

Papers

In Vivo Studies of the Evolution of Physical Properties of the Human Skin with Age

In vivo Biophysical Characterization of Skin Physiological Differences in Races

Do cosmetics enhance female Caucasian facial attractiveness

Influence of ageing on the in vivo extensibility of human skin at a low stress.

Morphometry of human epidermis in vivo by real-time confocal microscopy