Where to measure electrodermal activity?

This article explains the difference of using a wristband or a ring to measure your emotional intensity levels.

Moodmetric rings

Many things can get you emotionally activated. A close by situation with a colliding car can certainly light all the inner alarm systems, but milder things can also cause strong emotional reactions: seeing your children after a school day, a victory of you favourite basketball team or forgetting to buy paper for your printer.

With any emotional activation, your skin reacts and becomes a better conductor of electricity. This can be resulting from emotional or other psychological causes. The phenomenon is known as the skin conductance response or electrodermal activity (EDA). You may also run into an older term called galvanic skin response.

Based on the scientific research there are only a few places in your body where the EDA can be measured accurately and easily: the palms and the soles of your feet. These are the places where human body has the highest density of eccrine sweat glands that response to the emotional stimuli. You can measure the EDA elsewhere as well but the reliability is not as high or as easily achieved.

We want to bring to the market a very reliable and accurate measurement of emotional activation and intensity that is available for everybody. The choice for having a beautiful jewelry ring as the measurement form was an easy one.

It provides the best optimal measurement data that can be detected from the palm side of wearer’s hand. A ring is also a natural thing to wear and can be used daily as any other jewelry. It is easy to forget that this small, beautiful and non-intrusive jewelry detects your emotional levels and helps you in your life with its data.

What is moodtech? – Science behind Moodmetric

Moodmetric measures the electrodermal activity (EDA) of the skin, which is widely adopted in psychological research 1. EDA is generated by activity of the sweat glands.  Moodmetric measures the palmar skin on your finger. The palmar skin is the recommended EDA measurement location, since it has the highest sweat gland density2.

The unconscious actions of the human body are regulated by the autonomic nervous system. It consists of the sympathetic part and the parasympathetic part. The parasympathetic part controls the body’s rest-and-digest functions and the sympathetic part controls fight-or-flight reactions. When bodily functions are not of interest and the emotional side is, sympathetic nervous system is your choice.

The sweat glands are exclusively innervated by the sympathetic nervous system. This makes EDA an ideal measure for sympathetic activation.2 Electrodermal activity correlates to general emotional intensity, negative emotion, concern, and anxiety. 1, 3 These emotions cause almost similar electrodermal responses, which makes them very hard to differentiate. However, Moodmetric will tell you if certain parts of your day have brought up emotions or not. Inversely, Moodmetric tells you weather you are calm or not. This is particularly useful during your mindfulness, meditation and other calming exercises.

Mobile EDA devices have been used by scientists for some time2, 4, and now we bring this technology within everyone´s reach.

Signal accuracy

The signal accuracy has been proven in a study of 24 people by the Finnish Institute of Occupational Health by J. Torniainen et al.. The accuracy against a laboratory grade reference was found to be 83 %. They conclude:

“Clearly the ring sensor can be used to measure a valid EDA signal as indicated by the similarity of both event-related responses and the calculated features. The accuracy of the Moodmetric EDA Ring is adequate for psychological and physiological research when weighted against the advantage of conducting ecologically valid experiments outside laboratory conditions.”

The results have been accepted for publication in the 2015 conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2015, August 25-29).

Our measurement has been proven to be accurate also by University of Tampere, Finland. The correlation with the reference equipment Nexus-10-MK II was good. Comparison details in charts below.

image1 image2 image3 image4

1 Mendes, W.B. (2009). Assessing the autonomic nervous system. In: Harmon-Jones   E. ja Beer J.S. Methods in social neuroscience. New York: Guilford Press. p. 118-147.

2 Setz C., Arnrich B., Schumm J. and La R. (2010) Discriminating Stress From Cognitive Load Using a Wearable EDA Device. IEEE Trans. Inf. Technol. Biomed. 14(2). p. 410-417.

3 Nikula R. (1991) Psychological correlates of nonspecific skin conductance responses. Psychophysiology. 28(1). p.86-90.

4 Poh M.Z, Swenson N.C. and Picard R.W. (2010) A Wearable Sensor for Unobtrusive, Long-Term Assessment of Electrodermal Activity. IEEE Trans. Biomed. Eng. 57(4). p. 1243-1252.


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What does the future of meditation look like?

Today’s blog post is about the future of meditation and the possibilities that wearables such as the Moodmetric ring present.

One of the main reasons that people don’t meditate (other than lack of time) is that they don’t know how and are unsure if they are doing it right. With the advancement of technology there have been several steps towards overcoming these obstacles.  The introduction of meditation audio tapes made meditation easier and affordable since it wasn’t necessary to find someone to teach you meditation. The internet and meditation apps have naturally continued this transformation of making meditation more accessible.

Dan Harris highlights (in the video below) the science behind meditation and predicts that meditation will be the next big public health revolution. I believe that wearable technology such as the Moodmetric ring will be a part of this transformation by making it easier to track meditation sessions and by providing feedback.



Example meditation with the Moodmetric ring meditation app

Below is a screenshot of a 10-minute meditation I did after spending over 10 hours helping out at a video shoot for our upcoming campaign. Its worth pointing out that the final version of the app will look different, and the algorithms and accuracy will still be improved. This session was on the train ride on my way home, using mindfulness meditation (i.e. concentrating on my breath), and with gentle sounds of waves coming out of my headphones.The total score I received for the session from our algorithm is 78.6/100, which is my best one so far as I just recently re-started meditating.


When our current algorithm for measuring meditation is started, the first few minutes are spent making adjustments so that the rest of the data will be as accurate as possible. After 3 minutes you can start to see the effects of thoughts entering my mind as I am entering a meditative state. Especially after 8 minutes there is a significant drop in my meditative state, which was caused by an announcement that I was only two trains stops away from my home station. This prompted a thought: “did I remember to set the timing of the meditation correctly?” to come into my head, but I was able to let this go fairly quickly.

What do you think? Would you like to track your meditation sessions in this way?  Are wearables going to change the popularity of meditation?

P.S. This blog will have a lot more awesome content related to meditation in the future. If you are interested get on the newsletter (on the right side of this post) and follow us on twitter.

Science behind the Moodmetric ring

Emotional sensations such as excitement, happiness, anger and joy often involve a physical response, such as the heart pulsating with fear or the stomach lurching from anxiety.

Many of these physical reactions are controlled by the sympathetic nervous system, a branch of the autonomic nervous system, which controls involuntary body responses such as blood flow and digestion. The sympathetic nervous system is activated with controlling the body’s fight-or-flight reactions. When facing a threat, these responses automatically prepare your body to flee from danger or face the threat head-on.

When experiencing an emotion the sweat glands in the palm react and skin conductance increases. This phenomenon can ne measured and is known as electrodermal activity (EDA), skin conductance response (SCR) or alternatively as galvanic skin response (GSR). The Moodmetric ring detects the changes in skin and shows the emotion level changes in relation to user´s personal threshold values.

The measurement has been used in scientific study for over a hundred years. The Moodmetric ring data has been verified against scientific equipment, indicating high correlation and thus the ring is a reliable EDA measurement device.


The Story of Moodmetric

Our inventor Henry Rimminen, Ph.D., came up with the idea of implementing the standard electrodermal activity measurement with a ring in 2011.

The measurement technique itself was widely known but had mainly been in use in laboratories and universities. Consumer versions had been either bulky or not optimized to give meaningful data in a clear format.

Our dream was to provide everyone access to reliable emotion data. From the beginning we wanted to make a beautiful ring to wear in everyday life. It was also important for us that for the first time a wearable would show live emotion data in an easy-to-interpret way. Additionally we wanted to provide a simple yet accurate tool for stress measurement.


Henry´s development work started with a fun prototype and PC software. The first experiments started with a ring wired to a circuit board made of wood.

For the first wireless prototype, the electronics were stuffed in a party ring with lots of glue. These electronics still work today — it’s the device with a cord in the picture.

Soon after, Henry made several 3D-printed “death star” models using a flexible ring. The ring’s flex structure was easy to damage, but the signal quality amazed everyone.


The next development was a round model with a metallic ring. The ring part came in three sizes. It was quite heavy and spun easily, but was fully functional and very robust.

After a complete re-engineering of the PCB, Henry came up with the long and narrow model with a metal ring. It was very lightweight and fit the finger perfectly. There were contact issues with the steel chosen and battery life was low. However this prototype was the basis for the current commercial version.


For the final ring we brought in a jewelry designer – Vesa Nilsson from OZ Jewel in Helsinki. The perfect shape of the Moodmetric ring was born thanks to him.

3D-printed models were used to verify proper ring attachment and finger fit. This beta version features long battery life and significantly faster charging than any of the earlier models. It is splash proof and people love it!