Questions tagged [biopotential]
Instrumentation related to the measurement of bioelectric phenomena from the living system, such as ECG, EEG, EMG, and galvanic skin response.
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79 views
Bio-impedance circuit inputs
Recently, I wanted to build a replica of a bio-impedance circuit that I found in one of the NIH.gov papers. As obvious, bio-impedance circuits are usually used to measure body composition. They are ...
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3answers
137 views
Switching between low voltage recording of biologic signal, to high voltage stimulation
I am recording a biopotential signals (EEG ~microvolts), which I pass to a digital amplifier circuit (ADS1299). I am recording 8 channels. I would like to switch channels, one by one, with a voltage-...
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1answer
66 views
Voltage / amperage / setup for tingling sensation
There are small pens (powered by a single or double 1.5V battery) or other medical devices that upon touching your skin produce a tingling sensation.
Main question: I wonder to what voltage, amperage ...
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1answer
65 views
How to compare performace of EMG electrodes?
I'm working on building an acquisition system for sEMG signals. The problem I'm facing is how can I reliably measure the performance of different designs? Obviously I can just put the electrodes to my ...
0
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1answer
139 views
can you have a system with multiple anodes connected to one cathode (e.g.Battery, generator, biocell, solar cell)?
simulate this circuit – Schematic created using CircuitLab
Usually, the anode transfers electrons to the cathode. However, let's say the anode is not releasing enough electrons to create enough ...
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0answers
32 views
How to control the potential in multiple-electrodes (3 or more) in electrochemical cells?
Usually, in most cell designs, the concept of two-electrode design is the baseline. The two electrodes are anode and cathode where the electron transfer happens between them. However, I have been ...
0
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3answers
98 views
Multiplexing analog signals
I am designing a system to measure voltages from bio-potential sources and feed them into an ADC after filtering and amplification. The source has the following charactristics:
amplitudes are in 10's ...
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0answers
54 views
What is the difference between galvanic skin response and skin resistance of human skin?
I know this is not related electrical directly, but op amps and Wheatstone bridges are used in these applications.
I have seen, Wheatstone bridges with a differential amplifier are used in skin ...
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3answers
57 views
Noise in an unconnected biopotential electrode lead wire
My question stems from a particular statement on page 256 of the textbook Medical Instrumentation - Application and Design, Fourth Edition (by J. Webster):
Relatively high potentials can often be ...
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0answers
41 views
Single ended biopotential amplifier
I have to design a single ended biopotential amplifier circuit based on an already existing model for differential amplifier.
In other words, I have a circuit in which each channel has two inputs from ...
0
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3answers
39 views
Recording sensory nerve action potentials at the skin surface without electrical stimulus
I studied many nerve conduction studies. In these studies, there is one stimulator that excites the nerve and there are electrodes placed at the skin surface on the path of the nerves to record the ...
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2answers
243 views
How many / which electrodes should I use as input for an RLD (right leg drive)?
When reading through the datasheet of the ADS1298 (an analog Front-End for Biopotential Measurements) I noticed the schematic on page 42 (see below):
It is possible to select or deselect the positive ...
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1answer
42 views
Servo drive in biopotential amplifier
I have to design a bio potential measurement system:
AD converter and the connecting digital / software part
an analog amplifier stage: basically a regular ECG amplifier composed
of discrete ...
2
votes
2answers
106 views
Hand contacting op amp photodiode circuit causes interference - what ist the physic behind it?
I am new to analogue electronics and I am still learning about op-amps.
I use the most common circuit for amplifying a photodiode's signal to measure it with an ADC:
Amplification gain is 1M, the ...
0
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0answers
89 views
Whenever two system or sources are coupled they should have same current sink or common reference point (say ground). How to realize this in ECG?
Electrode (Ag-AgCl) are placed at different part and directly fed to positive and negative input of differential amplifier. How can we realize human body and amplifying system have same current sink ...
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4answers
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Why would you put your input amplifier in front of your filtering for an ECG signal?
In this article at eetimes.com they show the signal chain for measuring an ECG.
The raw signal of an ECG contains noise and offsets at least a magnitude larger than the real signal. (Some few mV ...
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1answer
152 views
Modify the AD8232 chip configuration to use only LEFT and RIGHT arm in steel leads configuration
I am an industrial designer (little experience with electronics) trying to modify one of the AD8232 chip configurations. The AD8232 is a Single-Lead, Heart Rate Monitor Front End. In the datasheet, ...
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5answers
2k views
Circuit for small level voltage detection (microvolts)
I have been working on a project lately which help in the detection myogenic potentials (of the levels of micro-volts).
After studying from several places, I finalized the following test circuit.
The ...
2
votes
1answer
83 views
Direct signal injection from function generator for EEG BCI calibration
I have seen several topics related to calibration of BCI and most of them use a "head phantom". But I want to know, is it possible to test the openBCI hardware directly using function generator? And I ...
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1answer
207 views
Can ECG electrodes be used for EEG detection?
Im having financial limitation for purchasing EEG monitoring modules or electrodes. But so is not the case for ECG. I am doubtful whether I can use ECG electrodes for EEG since brainwaves are in the ...
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2answers
144 views
Are electrodes mostly homogeneous or are there variations by usage, such as EEG vs EKG/ECG?
Are electrodes mostly homogeneous or are there variations by usage? My main usage is EEG. I have some interests in other areas and see similar electrodes sold for less money when marketed for ...
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2answers
403 views
Why is bipolar EMG better than monopolar at reducing (common mode) noises?
As defined in this post, the monopolar EMG can reduce the common mode noise by taking the difference of the two inputs, i.e. EMG_mono = k * (V1 - V2).
And, for bipolar mode,EMG_bi = k3 * [k1 * (V1 - ...
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1answer
62 views
Testing the integrity of cable shielding for suitability
I am currently working with an ECG cable, is there a way for me to test the integrity of the shielding of the cable without using it directly on an ECG monitor to check for interference.
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1answer
249 views
Is it possible to make a lightbulb light up by wetting your hands? [closed]
I was recently watching an Electroboom video on free energy devices, but my question is not about any of that stuff. Here's the video. At about 5:50 he claims and seemingly shows that he can light up ...
0
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1answer
2k views
Is there any difference between AD620 vs INA128?
I'm trying to make an EMG sensor.
I've found some tutorials, for example, DIY muscle sensor/EMG circuit for a microcontroller, but my main question is can I make an EMG sensor using AD620 instead of ...
0
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2answers
158 views
Recording of sensory nerve evoked potential generated through skin-receptors [closed]
If we touch / give pressure to a skin, there are many mechano-receptors like meissner/pacinian corpuscles that produce action potential in neurons.
I am in a need to detect those action potentials ...
4
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2answers
274 views
Does anyone have advice on homemade EKG/ECG leads?
I'm not sure this is where it should be posted, so apologies in advance, but I'm working with an Arduino and Sparkfun's heart rate monitor AD8232 (https://www.sparkfun.com/products/12650) to gather ...
0
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0answers
104 views
why is ad620 output signal disappearing after connecting the right leg drive to the human body?
I am building an ECG sensor based on the AD620 instrumentation amplifier. The circuit is amplifying minute(50uV) signals from the signal generator perfectly. The total gain of the circuit is around ...
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1answer
487 views
How to Calculate the Impedance of the Capacitor T network?
I guess Capacitor T network used in the schematics is for Impedance matching, if yes how to calculate the impedance of the same circuit?
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0answers
126 views
why is the gain of ad620 not responding to the change in( Rg), the gain resistor?
I am building an ECG sensor based on the AD620 instrumentation amplifier.For the purposes of testing , i have built a simple AD620 circuit with pin 2(-) and pin 3(+) connected to a 2.82mV(peak to peak)...
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1answer
228 views
Using AD5933 with an external amplification to measure changes of permittivity
I'm going to try and explain my problem statement first and then explain my solution and then ask for suggestions.
So, my problem statement is this: To determine changes in permittivity from a ...
0
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2answers
117 views
Help with identifying a transfer function - with neuroscience application
This is a question for you electrical network engineers. The problem has arisen in a neuroscience study I am working on, but I hope to be able to glean some insight from other domains that deal with ...
0
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2answers
284 views
Can Texas Instrument's INA332 really be used for EEG?
On TI's datasheet, it specifically lists EEG as one of INA332's potential uses.
EEGs are microvolt level signals, and the INA332 has input offsets of +/- 2 milliVolts.
73db CMRR is quite low, but ...
0
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1answer
77 views
University Project - Common Mode feedback in EEG systems
Basically EEG signals (potential from brain) contain 'noise' due to EMG signals (potential from muscles). I was thinking of using the EMG as a common mode feedback prior to the amplification of the ...
1
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1answer
74 views
Patient protection in a biopotential amplifier
My question is in regards to biopotential amplifiers, more specifically an instrumentation amplifier as part of an ECG.
I know that IEC60601 states that a paitent must be limited to 50uA under fault ...
1
vote
1answer
182 views
Signal Processing of a raw EMG signal
I am a student. I acquired EMG signal (sampled at 1KHz) by using dry electrodes. At first, it was all noisy. I then applied a Notch Filter (@50Hz) and the signal looks better but still not great.
Any ...
4
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2answers
3k views
ECG circuit Pre amplifier
I am in the process of designing an ECG circuit to detect heartbeat abnormalities. I have two question regarding the AD8220 datasheet:
What is the function of the 2.2pF, 10pF capacitor, 10k, 15k ...
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4answers
2k views
why is a GROUND electrode needed with a referential amplifier?
Physiological amplifiers seem to often (always?) have both ground (G) and reference (R) electrodes along with one or more active (A) electrodes.
Typical voltage at an active site is determined AFAIK ...
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0answers
47 views
Understanding what Electrode Impedance values mean on Spec sheet
I want to understand what the electrode impedance values given on spec sheet mean. Just looking to gain a general understanding and what voltages/ currents I can or cannot use. The electrodes are used ...
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3answers
5k views
What does this op-amp circuit do? (part of an ECG)
I would like create an ECG circuit based on this schematic (from the AD620AN datasheet):
I don't know this part of the circuit and how it works. I know this is called a right leg driven circuit which ...
0
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0answers
162 views
Voltage drops across a Human Body (Set gain of InAmp)
I'm developing an application that sends an electrical signal to the human body. It is a bioimpedance system.
This signal has approximately 3.2Vpp ranging between + 1.6V and -1.6V, at a frequency ...
1
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1answer
184 views
Do certain types of electrodes work better than others in an area with hair?
In selecting components for an EEG development kit, I'm wondering if certain types of electrodes capture signals better in the presence of (a small amount of) head hair?
For instance options include:
...
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0answers
57 views
How CMOS transistors might be used as a capacitive sensor for biopotential?
I was wondering how CMOS-based capacitive electrodes might be designed (e.g. in this article I stumbled on). It seems to me, that it would make sense to capacitively couple the input of the transistor ...
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1answer
258 views
Can we have the action potential an AC current [closed]
as well known brain are connected to our body by neuronal cells. it transmits and receives its data by action potential during neuronal cells. i wonder if any one can explain to me the properties of ...
0
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2answers
946 views
EMG, Muscle Sensor Arduino - Troubleshooting [closed]
I've been testing the EMG sensor below:
http://www.ebay.com/itm/Muscle-Sensor-EKG-EMG-Developemt-Electronics-Module-Interface-Kit-For-Arduino/351850511727?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=...
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2answers
348 views
Switching input to instrumental amplifier with an analog mux (ECG, EEG)
I'm trying to find a cost effective method of taking samples of electrical signals of the body (and potentially plants).
Can you have one high precision instrumental amplifier and then use an analog ...
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1answer
191 views
How to test an EEG?
Apologies out of the gate here as I'm a CS person with not a huge amount of experience in electronics, so this might be a pretty basic question. I've built basic EEGs before, basically electrodes ...
0
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1answer
75 views
Transimpedance amplifier with biopotentials
I have a PPG sensor to be specific the sensor is called " easy pulse finger sensor " which is a ( phototransisitor), can it be connected to a transimpedance amplifier ( current to voltage converter)?!...
0
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1answer
321 views
50 Hz noise only in chest leads of 12 lead ECG
I am implementing a 12-lead ECG signal conditioning circuit. With the current design the bipolar leads (lead-I and II) are of sufficient quality with no visible 50 Hz noise. However, the unipolar ...
0
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1answer
410 views
Can you measure the voltage produced in the heart using an oscilloscope or multimeter
Can you measure a PQRST wave using a multimeter or oscilloscope, it you can will two leads be enough and why are 12 leads standard tor ECG monitoring?
