ROY sensor – Skin humidity sensor

I am thinking to use a Bioelectric Impedance Analysis(BIA) Sensor from a digital skin analyzer to analyze skin humidity and oil conditions.
A few weeks ago, I went to ‘The Body Shop’ (A cosmetic brand) to buy a moisturizer. And a staff used the skin analyzer to test my skin conditions.  I have doubts about whether the data is true or not.  I found this skin digital analyzer in Amazon.

I thought it was cool because it shows two values; skin humidity and oil, so I bought it. Frankly, I am not sure what I am going to do with this sensor, but I bought it.  I was curious about continuous skin conditions depending on situation, time and applied moisturizer.
I wonder how it works and I started to disassemble it.
It comprises a BIA sensor, power/reset push buttons, an LCD & led panel, a battery holder and a buzzer.
I wanted to get the values from Arduino, but I could not do. So I unsoldered the only sensor part and connected to Arduino.  I used the Arduino Graph example code with Processing.

I only check the skin moisture value from the sensor, I am not sure how to get skin oil value. This value could be same if I were used two conductive metal to get the resistor value.





< Test Result >

  • fingertips show the most humid value. (50~500)
  • Palms has the higher moisture value than other skin area.
  • the back of hands (except palm area) shows around 0~5 (hardly sensing)

  • Just after applying moisturizer, the figure increased and it lasts less than 1 min.

(Left) after applying moisturizer within 1 min | (right) 2min later  – Physiogel Lotion 


  • I am not sure how to get oil value from the sensor. ( I think I should use the processor chip inside of the original devices.)
  • Getting more sensitive and fine value from Arduino. (Original LCD shows the more detailed value.  )
  • Checking this value constantly (e.g 24hours), but not frequently(e.g. every 30 min)
  • Finding the best skin area to examine.

<Plan (…Hope)>

  • Build a wearable or attachable device, accessory or chip


  • Send the data wirelessly ( maybe NFC, Bluetooth …)
  • Simple application to record where I am sensing and time
  • Alarm the dehydrated condition

Frankly, I am not sure the result from the sensor, is moisturizing important? should I use the expensive and high nutritious cosmetics? How many times should we apply them? I am not sure but I hope to find any interesting data from my ROY sensor.


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