From the first paper “Skin Mechanical Properties and Hydration Measured With Mobile
Phone Camera”, they use smartphone’s camera to measures dehydration value from user’s skin
which has 2 methods, Skin marked test and Skin texture test. They record video 720p at 30 fps
and use image processing to calculate hydration value by 2 following methods. From second
paper “Dehydration Prevention and Effective Support for the Elderly by the Use of
Smartwatches” , they use smartwatch’s sensor to detect drinking in daily life. This smartwatch’s
application has database that contains times to drink compares with age of user. Smartwatch will
remember times that user drink water per day and it will reminder user “You are in dehydration
now, please drink some water.” by no need hydration measure method.
From third paper “Development of diagnostic sensors for infant dehydration assessment using
optical methods” , they use three non-invasive optical sensors in this test because this paper want
to test, what’s the most appropriate sensor. They use CRT (Capillary refill time sensor) which is a
small camera inside sensor box record video as 720p at 30 fps and use image processing to
calculate hydration value by using monitor amount of blood flow to tissue. And next sensor is SRT
(Skin recoil time sensor). It’s same to CRT but record as 480p at 90 fps and record recoil of skin
while physician test. SRT still use image processing and time counter to process result as same as
CRT. The last sensor is ST (Skin temperature profile sensor). It used to measure skin surface over a
prescribed path on the subject’s body. Then they gather value from each sensor and write it in
graph and summarize. In this paper, they use specific tools that can’t use by himself and hard to
use , need to summarize by physician because you don’t know means of result (graph).
So the second paper is the best way to measure hydration is method of first paper that
used smartphone’s camera because it’s easiest to measure. It will be better if we use method
from second paper to remind us to measure again for surely by smartwatches.