Review Reports - Review of Modern Techniques for the Assessment of Skin Hydration

Round 1

Reviewer 1 Report

The authors have written a reasonably comprehensive review on modern techniques that can be used to measure skin hydration. A broad spectrum of techniques is described and the working principle explained. Applications cover the cosmetic field and dermatology. It is evident that the authors themselves are less familiar with dermatology and medical terminology (for example on page 14 the term "atopy skin" is used, where better "atopic skin" can be used), while the whole review is punctuated with many technical details and abbreviations.

My suggestion is to bring this more in balance and to add a listf abbreviations.

Specific points:

Abstract: "skin hydration is a complex mechanism"; I think that "mechanism" is not exactly the right term; it is rather a process or a chemical / biological system.

Figure 4: The white bar from the figure in the original article is missing.

The references are listed twice at the end of the manuscript.

Author Response

Dear reviewer

Many thanks for your valuable comments and suggestions. Please see below a point-by-point response to your comments:

Comments and Suggestions for Authors

The term “atopy skin” has been changed to “atopic skin” as recommended. We have reviewed the remainder of the manuscript, and where possible, have tried to use medical terminology. However, given that our background is in Physics and Biomedical engineering, the reviewer may find additional terms that are not commonly used in clinical practice, and in which case, we would have happy to amend them.

My suggestion is to bring this more in balance and to add a list of abbreviations.

A list of abbreviations has been added to the manuscript.

Specific points:

Abstract: "skin hydration is a complex mechanism"; I think that "mechanism" is not exactly the right term; it is rather a process or a chemical / biological system.

Changed to “process”.

Figure 4: The white bar from the figure in the original article is missing.

The SC is shown in the figure as the first layer of skin, which is the white coloured line, and the rest of layers in green. The figure caption has been re-worded to avoid confusion.

The references are listed twice at the end of the manuscript.

The latex code has been corrected.

Kind regards

Reviewer 2 Report

The article is well organized scientifically sound and reviews the current techniques being used in measuring skin hydration. The authors describe the principles of operation and the method applications in skin-related research.

First the authors review the traditional methods such as capacitance, TEWL and mechanical-based techniques which are considered the standard in skin-related measurements, and use SC water content as a primary factor in determining SC hydration and barrier function without precisely analysing its composition nor its structure. They describe the advantages and the disadvantages of the methods and refer some examples of instruments.

In a second step the auhtors describe the use of spectroscopic and imaging techniques suitable for skin measurements and detailed analysis of skin structure and composition in relation to skin hydration and barrier function. Spectroscopic techniques such as OTTER, IR and NIR, and Raman are well-established for skin related measurements and enable assessment of multiple attributes including SC thickness, water concentration gradient within the SC, and lipid molecular organisation. Also they refer the operation principles of the most important instruments.

I would like to suggest to the authors to add some advantages for the use of

"NIR spectroscopic instrumentations with flexible fibre optics as well as portable NIR spectrometers". Are there any previous research or references for this topic related to the skin research?

Author Response

Dear reviewer

Many thanks for your valuable comments and suggestions. Please see below a point-by-point response to your comments.:

I would like to suggest to the authors to add some advantages for the use of

"NIR spectroscopic instrumentations with flexible fibre optics as well as portable NIR spectrometers". Are there any previous research or references for this topic related to the skin research?

The following advantages have been added: reduced costs, less restriction on selection of examination site, and increased stability against environmental conditions such as temperature and relative humidity.