Raw data can be measured, but absolute values are no longer displayed. Is it a malfunction?

My MUSE and MUSE Monitor have worked fine for the past year. Signal quality problems could be solved by using gels, skin creams and bandanas depending on the situation.

However, on October 16, a signal indicating that “the signal quality was poor” (Photo. 1) appeared.

When checked with MUSE Monitor, the raw data is displayed normally, so there seems to be no problem with the contact between the sensor and the skin (Photo. 2).

However, when I look at the absolute value on the Muse Monitor, the signal is displayed as a constant value, which seems to be abnormal compared to the raw data. (Photo. 3)

My guess is that “there is no problem with the Muse Monitor”.
But rather on my MUSE (model MU-02) main body, “The raw data is detected normally, but the function to analyze the absolute values ​​of the brain waves (α, β, γ, δ, θ) may have trouble."

But, I am not sure about the inside of MU-02.

I’m currently inquiring about MUSE support, but has anyone experienced a similar phenomenon?

The empty black circle on the HSI (Horse Shoe Indicator) shows that the Muse is not being detected on the head. In this state no absolute values are calculated.

This “headband on” status uses the front three pads on the sensor strip. Clean them very gently with rubbing alcohol. Also check they are making firm contact with the head by getting a friend to look at the strip from above when you are wearing it.

Lastly, sensor contact problems occur more often as winter approaches and it gets colder out. People turn on heating systems and get dry skin. So you can also try gently exfoliating the forehead.

Thank you very much, Enigma644 ,for your advice.

To improve the contact between the MUSE electrode and the forehead skin, I use to apply water-based skin cream to the electrode and my forehead every time, and fixed MUSE to the head with a bandana.
If the ear electrode still causes poor contact, a medical gel is applied to the conductive rubber electrode of the ear.

In this data, you can see that the contact between the electrode and the head was good because the raw data of Photo2 was collected normally.
What “normally” mean is that in order to verify the recording function of raw data, two types of test operations, “eye blink” and “bite jaw”, were performed, and these myoelectric signals were converted to MUSE raw data. I confirmed that it was recorded with “normal waveform and amplitude”.

Therefore, I think that the raw data of Photo2 is the technical evidence that “the electrode contact was normal”.

On the other hand, as you teach me, the MUSE main unit has an algorithm that “the empty black circle of HSI (horse shoe indicator) has no muse detected in the head and the absolute value is not calculated”.

So, logically

  1. Raw data was measured by MUSE Biological preamplifier, and transferred to MUSE Monitor via MUSE MPU.
  2. So, raw data was collected by MUSE and entered into the MPU, but the algorithm to calculate the absolute value did not work.
    So, in the Photo.2, HSI has an empty black circle.
  3. Therefore, there is a possibility that the phenomenon “raw data could be collected, but absolute value cannot be calculated” that does not occur normally has occurred.

I think that.

So far, please let me know if I heve any technical or logical mistakes.
Please.

Correct.

I can re-create this situation on my device by blocking specific pads with paper and then putting on the Muse.

The sensor strip has 5 pads. From left to right: 1,2,3,4,5.
If you block off pads 2 and 4, you will get this situation with RAW data from all main sensors, but the head not detected.

Also you may notice that the signal is much more susceptible to power line interference.

Great!
And, sincerely thank you.

The sensor strip has 5 pads. From left to right: 1,2,3,4,5.
If you block off pads 2 and 4, you will get this situation with RAW data from all main sensors, but the head not detected.

I agree exactly.
When this phenomenon occurred, I found the electrodes 2 and 4 were discolored.
Please have a look at the photos.

The part of my forehead that was in contact with electrodes 2 and 4 was also brown and did not fall off after washing or rubbing. Fortunately, after 5 days, the MUSE “brown kiss marks” on my forehead has disappeared.

Also you may notice that the signal is much more susceptible to power line interference.

I have solved this noise issue. Please see my post below.

I am currently inquiring to MUSE support, but I received the answer that includes “MUSE Monitor is not our product”, at present.
Hopefully this person’s boss will give me a consultation.
I am very in trouble.

I just hope this person’s boss is reading this Muse Forum.






Additional Notes 2019.10.23

I would like to thank all those involved including MUSE Forum readers.

As of today’s morning, I received an email from MUSE support stating like that “We will accept additional technical questions and forward the information to senior engineers.”

So, I will try to ask technical consultation including more detailed data.

This abnormal phenomenon seems to be very unusual.
Even if my EEG measurement method contains an exceptional application case (?) that exceeds the manufacturer’s warranty, I would like to work with the manufacturer’s engineers to avoid the problem so that the phenomenon does not recur.

Anyway, thank you very much.

The following document states that MUSE has research-level EEG measurement quality and introduces the availability of external electrodes.

Choosing MUSE: Validation of a Low-Cost, Portable EEG System for ERP Research
(My Note: Please see Table 1, Note c)


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Therefore, I also used my MUSE, which is in a state where raw data can be measured, and I connected external electrodes.
Fig.1 and 2 show the electrode attached to the back of the head (I modified ECG electrode).
Fig.3 is the raw data including the signal of the external electrode.
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The length of the shield wire between the external electrode and the USB connector is about 2m.
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Since the myoelectric signal was included by tilting the neck, it seems that the measurement with the external electrode is somehow done.
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The next step is, to verify the measurement quality of the external electrodes.
I would like to measure brain waves on the scalp very close to regular electrodes such as AF7,AF8, TP10 and TP9 using external electrodes as comparison data.

If I do so, what happens, including responce of the common mode rejection electrodes?

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Therefore, I would like to contact the manufacturer for the following.
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Question 1.
Is the usage of external electrode of Original Muse (MUSE-02) out of the manufacturer’s warranty?
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Question 2.
If the manufacturer allows it to be used at the user’s own risk even if it is not covered by the warranty, is there a site that discloses technical instructions?
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Question 3.
If the use of the external electrode of Original Muse (MUSE-02) is prohibited for some reasons, for example, please tell me where to place the notice that the use is prohibited.


Fig.1 Experimental equipment


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Because the noise of the external electrode is too loud, I remade the cable for the external electrode.


In addition, I chose a place with as little power supply noise as possible.

EMG of blinking eyes can be recorded as usual.

Fill%20the%20bathtub%20with%20cold%20water%20in%20a%20dry%20bathroom%20and%20blink%20eyes

In this state, when the head is tilted, myoelectric signals are clearly recorded as the head moves.

Filled%20the%20tub%20with%20cold%20water%20in%20a%20dry%20bathroom%20and%20tilted%20head

If there is a reply to the question email I sent to the manufacturer, I would like to inform to Muse Forum readers.

Without this sequel, it means that the technical answer to the question did not come from the support service.

By the way, I have used the broken MUSE (black) for over a year, so I intend to buy a new MUSE (white) for meditation.

Aside from the support service, I do like MUSE.

This morning( in Japan time), I received an email with the word “report progress” from MUSE user support.
Thank you, so much.

However, the answers to the three questions have yet to come.

Question 1.
Is the usage of external electrode of Original Muse (MUSE-02) out of the manufacturer ’s warranty?
.
Question 2.
If the manufacturer allows it to be used at the user ’s own risk even if it is not covered by the warranty, is there a site that using technical instructions?
.
Question 3.
If the use of the external electrode of Original Muse (MUSE-02) is prohibited for some reasons, for example, please tell me where to place the notice that the use is prohibited.

In order to expand the use of MUSE as equipment for academic research, I would like the manufacturer to provide public notices on the use of “external electrodes”.

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今朝(日本時間)、MUSEユーザーサポートから「進捗状況の報告」という単語が記載されたメールを受け取りました。
どうもありがとうございます。

ただし、3つの質問に対する答えはまだ出ていません。

質問1。
Original Muse(MUSE-02)の外部電極の使用は、メーカーの保証範囲外ですか?

質問2。
製造元が、保証の対象外であってもユーザーのリスクで使用することを許可している場合、技術的な指示を使用しているサイトはありますか?

質問3。
何らかの理由でオリジナルミューズ(MUSE-02)の外部電極の使用が禁止されている場合、使用が禁止されていることを通知する場所を教えてください。

学術研究用の機器としてのMUSEの使用を拡大するために、製造業者に「外部電極」の使用に関する広報をお願いします。

Thank you so much.

Welcome to the Muse SDK Documentation

MUSE, which is also sold at Amazon, what is happening in this photo?

AUX-R is Pin 4 on the USB port.
You will get static on this unless you connect an auxiliary electrode. What you’re probably seeing is hair touching the ground plane of the USB port. If you tap the USB port with your finger you’ll see the data jump up and down.

If you tap the USB port with your finger you ’ll see the data jump up and down.

Thank you so much for the advice.

I tried to bring my palm close to the USB port.
As you pointed out, a large signal has been observed.

To the readers of the forum.
Comparison of signal waveforms observed in a living room with 50Hz noise, and a dry bathroom where the 50Hz noise disappeared.

When we use external electrodes, it is likely to break MUSE if we are not familiar with big effect of electrostatic induction and electromagnetic induction for MUSE.