The Moodmetric smart ring for preventive stress management is an invention of a Finnish company Vigofere Oy. The inventor Henry Rimminen (Ph.D.) has a solid background in sensor technology and physiological measurements. He came up with the idea of incorporating the electrodermal activity (EDA) measurement into a ring in 2011. The phenomenon measured is also known as skin conductance (SC) and galvanic skin response (GSR). The measurement signal accuracy is comparable to laboratory devices and the research by the Finnish Institute of Occupational Health (Torniainen et al. 2015) has found the device valid for field research.

Electrodermal activity (EDA) is one of the most studied psychophysiological markers of the functioning of the autonomic nervous system and it has been applied in psychophysiological research for over 100 years (Boucsein 2012). EDA is an indicator of the sympathetic activity of the autonomic nervous system that is associated with emotion, cognition, and affection (e.g. Critchley 2002).

The skin becomes a better conductor of electricity when the eccrine sweat glands process sweat to skin surface. Eccrine glands are innervated by the sympathetic nervous system and are part of ​the fight or flight response​ system. The palmar site of the skin or sole provide the best measurement points due the great intensity of the eccrine sweat glands. (e.g. Boucsein 2012.)

The Moodmetric index is calculated by an algorithm developed by Vigofere Oy. It describes arousal of a person on a scale of 1 to 100. High arousal can be both positive and negative, e.g. being enthusiastic or in anguish. The sympathetic nervous system is very active. When the index numbers are low, the parasympathetic nervous system works and enhances recovery. The Moodmetric index daily average number is an indicator of the balance of the autonomic nervous system. This balance is important when the target is to prevent chronic stress. Clinical studies starting in spring 2018 aim to further validate research based information supporting these hypothesis.

There are little ambulatory measurement applications for stress available. Long term measurement is needed when a) wanting to understand is high stress load momentary or going on for weeks or months indicating chronic stress b) motivating a person to efficient stress management with real time feedback. The Moodmetric smart ring fits these purposes well. Read more about physiological measurement of stress in our series of five articles:

Diseases relating to the functionality of the autonomic nervous system may affect electrodermal activity. Patients with hyper- or hypothyroidism have been recorded with unusual EDA measurements (e.g. Dolu et al. 1997; Dolu et al. 1999). Within a variety of anxiety disorders (e.g. panic disorder and posttraumatic stress disorder), increased electrodermal activity and reactivity has been observed (Braune et al., 1994; Hoehn et al., 1997, Lader & Wing, 1964; Blechert et al., 2007). However, in depression electrodermal activity is often reduced (Argyle, 1991; Ward et al., 1983). Electrodermal activity measurement has not been largely applied in clinical research until now. It has been limited to laboratory environment before the entry of wearable devices.

Download PDF with references here
The Moodmetric cloud service

From the mobile app it is possible to download the data to the Moodmetric cloud. The cloud enables long term remote monitoring, and uploading the data from the cloud to further analysis in csv or excel format.

The Moodmetric Cloud Service Dashboard

The users can synchronize data from several smart rings to the cloud platform, and also export the data as CSV-file from the platform. The platform includes also a service for group monitoring, e.g. for monitoring the stress of teams or other organizational units. The platform provides also APIs for accessing the data and enabling to build third-party services.

The data sync from mobile to app is by default set to every three hours when within WiFi connection. The cloud data is thus possible to view almost real-time.

While the Moodmetric ring measurement sample rate is 3S/sec, the ring stores only 1 sample per minute. This is due to memory size limitation, and the intended use of the Moodmetric ring. The ring is primarily targeted to long term and continuous follow-up on stress levels, where the stored measurement points are sufficient. The stored ring data is transferred to cloud is thus also 1 sample per minute.

In the case of the Moodmetric smart ring, the data can be exported from the mobile device or accessed via the cloud. The most straightforward way is to download data from the cloud to excel or csv.

From the cloud the following data points can be accessed. However, for consumer use or long term stress management we always advice to use the indexed MM level. This is the most informative figure, and reliable also when the Moodmetric ring has been worn in normal circumstances. When the SCL or SCR levels are used, should a laboratory setting be applied.

The Moodmetric smart ring datalog

From the cloud the datalog can be also downloaded as a CSV-file. The CSV-file is nearly identical with the datalog table presented above, however, the synchronization information is only stored in the mobile device and the CSV export from cloud contains device_id as additional variable.

API (Application Programming Interface)

The Moodmetric API makes it possible to benefit from data in the Moodmetric cloud. The Moodmetric API is a partner API type and available upon request. It is shared with companies building e.g. health data platforms. The aim is to increase use and awareness of the EDA signal by providing an open API to all requestors with appropriate solutions. Via the Moodmetric API it is possible to access the same datalog as described above.

SDK (Software developer KIT)

The Moodmetric SDK allows everyone to develop their own mobile applications using the Moodmetric measurement data. To ensure operation of 3rd party applications in any mobile platform or computer operating system, Moodmetric provides interface documentation directly to the ring. The platform running the 3rd party application must be bluetooth smart ready.

You can download the SDK for free here.

With the SDK you can access e.g. the Instant Indicator and the Moodmetric Index / MM level.

The Instant indicator

The Instant indicator is a fast indicator on how the person reacts to different stimuli. These can be what you see, hear, smell or sense by touch at a certain moment. The response can be seen as an upward spike, which starts approximately after 1.5 seconds after the stimulus and peaks approximately after 2.5-3.0 seconds

The Moodmetric Index

The Moodmetric Index / the MM level is a continuous indicator on the wearer´s stress level on a scale of 1 too 100. The index is resistant to motional artefacts and comparable among different users.

Access raw data with the Windows PC logging software

The Moodmetric ring does not store raw data due to limited memory size. The Moodmetric ring measurement raw data can be accessed only by direct streaming from the ring to a Windows PC via a certain type of BLE dongle.

You can download a free package with drivers and short instructions here. Please note that this tool is primarily for research use, and we can not provide excessive user support for it.

Contact [email protected] for more information

Frequently asked questions

Read more

A short review and primer on electrodermal activity in human computer interaction applications (Benjamin Ultan Cowley, Jari Torniainen)

Past Moodmetric research projects with Universities


University cooperation and research projects: Jari Jussila –  [email protected] +358 40 717 8345