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!