Size Determination of Polystyrene Sub-Microspheres Using Transmission Spectroscopy

Round 1

Reviewer 1 Report

The paper “Size determination of polystyrene sub-microspheres using transmission spectroscopy” developed a simple method to identify the size of polystyrene (PS) nanospheres at the diameter range of 200-800nm. The paper clearly indicated the protocols on synthesizing the nanospheres, transferring the PS nanospheres onto glass substrate, and measuring them with UV-Vis spectroscopy. In the transmission spectrum for closely-packed nanospheres on glass substrate, the authors found a specific dip for different sizes of PS nanosphers at a Z value around 0.7, which is able to be used to calculate the PS nanosphere size by the wavelength of the dip. Because PS nanospheres are widely used in nanofabrication and material preparations, I would recommend the publication of this paper on Applied Sciences with following minor revisions.

1. In lines 122, 133, 152, the word “Figure” is missing.
2. In lines 227-230, the authors stated that “Therefore, we can use a simplified model of the free-standing 2D lattice of the dielectric sphere and then scaling properties of Maxwell’s equations [29] to calculate Z* for dielectric spheres of other materials ?∗=?√?/?∗ where ?=2.25 and ?∗ are the dielectric constants of the polystyrene and other material, respectively”. This is not a clear description, maybe authors can make this point clearer. In Figure 4(a), the PS nanospheres at ?=2.25 with 710 nm diameter have a dip wavelength of 860 nm around. In Figure 4(b), if we simply use this equation, the ?=2.0 and d=710nm nanospheres should have a dip wavelength of (√0/2.25) x 860 = 810 nm, while the actual dip in Figure 4(b) is at 780 nm. Similarly, ?=2.5 and d=710nm nanospheres should have a dip wavelength of  (√2.5/2.25) x 860 = 906 nm, while the actual dip in Figure 4(b) is at 870 nm. So the equation ?∗=?√?/?∗ is not valid for direct calculation of nanosphere size. For nanospheres with different ?, a similar equation as Eq. (1) should be recalculated by simulations.

Author Response

Dear Mr./ Ms. Reviewer,

We want to thank you for reviewing our manuscript. We appreciate your positive and constructive comments. We have addressed the feedback and improved our manuscript. Details of our response as following:

(1) In lines 122, 133, 152, the word “Figure” is missing.

We want to thank the reviewer for going over the manuscript thoroughly. We have removed the auto cross-references in the text, which cause the error of missing word “Figure.”

(2) In lines 227-230, the authors stated that “Therefore, we can use a simplified model of the free-standing 2D lattice of the dielectric sphere and then scaling properties of Maxwell’s equations [29] to calculate Z* for dielectric spheres of other materials ?∗=?√?/?∗ where ?=2.25 and ?∗ are the dielectric constants of the polystyrene and other material, respectively”. This is not a clear description, maybe authors can make this point clearer. In Figure 4(a), the PS nanospheres at ?=2.25 with 710 nm diameter have a dip wavelength of 860 nm around. In Figure 4(b), if we simply use this equation, the ?=2.0 and d=710nm nanospheres should have a dip wavelength of (√0/2.25) x 860 = 810 nm, while the actual dip in Figure 4(b) is at 780 nm. Similarly, ?=2.5 and d=710nm nanospheres should have a dip wavelength of  (√2.5/2.25) x 860 = 906 nm, while the actual dip in Figure 4(b) is at 870 nm. So the equation ?∗=?√?/?∗ is not valid for direct calculation of nanosphere size. For nanospheres with different ?, a similar equation as Eq. (1) should be recalculated by simulations.

We want to thank the reviewer for carefully checking and pointing out our slip in extending the method for the nanospheres of different dielectric constant. We have rewritten our statement mentioned above (lines 227-230) and agree with the reviewer that parameter Z for nanospheres with different e should be recalculated by simulations.

Sincerely,

Reviewer 2 Report

Very interesting, well written article.

The main question addressed by the authors is the way to determine the size of polystyrene (PS) nanobeads. The subject is interesting since the PS beads play a crucial role in many modern applications. Authors enumerate these applications in their article.

The authors prove that simple measurement of transmittance can replace expensive techniques to define size of polystyrene (PS) nanobeads forming array because they reveal reliable results.

The paper is very well written, clear and easy to read.

Author Response

Dear Mr./ Ms. Reviewer,

We want to thank you for reviewing our manuscript. We appreciate your positive and encouraging comments.

Sincerely,

Reviewer 3 Report

Dear Authors

I think that the presented results are likely to be of interest to the readers of Applied Sciences.
The manuscript is well-written. In the section Featured Application, using a simple language easy to understand by the general reader of the journal, you clearly define a problem and why it is important to solve it. The solution to the problem is explained and the impact on the field is mentioned.  
The introduction provides sufficient background but does not include all relevant references.
The results are clearly presented. Regarding the English language and style, I do not feel qualified to judge them but I understand all sentences and found no ambiguities.
In my opinion the work is interesting and novel. I recommend publication after minor revision.

In the attached pdf file, you will find several of my minor comments.

Best wishes

Comments for author File: Comments.pdf

Author Response

Dear Mr./ Ms. Reviewer,

We want to thank you for reviewing our manuscript. We appreciate your positive and constructive comments. We have addressed the feedback and improved our manuscript. Details of our response as following:

(1)  The introduction provides sufficient background but does not include all relevant references.

We want to thank the reviewer for introducing us to more recent works regarding the application of the polystyrene microspheres. We have cited works done by prof. Rozynek’s group in 2018 – 2020 to make the background of the introduction more complete and up-to-date.

(2) I recommend publication after minor revision. In the attached pdf file, you will find several of my minor comments.

We appreciate the reviewer’s time and effort for going over the manuscript thoroughly. We have corrected the way presenting measurements, units, superscripts, and subscripts following Instruction for authors at the places highlighted by the reviewer and wherever it is applicable throughout the text.

Sincerely,