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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How does this EEG safety circuit work?
I'm trying to understand the following circuit, which I found in this document (on page 5). The purpose of the circuit is to go between a set of EEG electrodes and an EEG signal amplifier, and protect ...
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How to measure skin-electrode impedence of dry eeg electrodes without an impedence analyzer?
I understand how to measure the impedance with an impedance analyzer, but I'm curious if it's possible to create a impedance measurement system on some kind of wearable with eeg electrodes. What's the ...
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INA333 strange output, it's the same w/ and w/o input
This is the EOG (Electroencephalography circuit I'm working with)
The output is essentially noise when I hook up the electrodes to myself, hence I'm debugging each stage, hooking up to an ...
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Voltage reference vs voltage bias for EOG circuit
This is continuation of my previous question.
I'm confused about the reference voltage and bias voltage.
As seen in the image above, the supplies for the INA333 and OPA2335 are clearly 3.3V and ground....
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Instrumental amplifier outputs in 12 lead ECG [closed]
Currently we are trying to build 12 lead ECG circuit, so we just need to know the answers to couple of questions. Why do instrumental amplifiers on given circuit have two outputs? How are they ...
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How to design gain based on input voltage and ADC voltage range?
What are the parameters to consider when designing gain amplification whether it be 2- or 1-stage (why one or the other?) when given an input and an ADC? I see for the same kind of signal (biosignal) ...
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Calculate parameters of active high pass and low pass filter given for EOG circuit
The circuit is from here.
The opamps are : OPA2335 (dual channel because of horizontal and vertical electrodes.)
I don't exactly understand how to calculate R and C values based on the 0.5 high pass ...
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3 electrode EOG system design
I'm trying to design an EOG system based on how the JINS MEME glasses did it. 3 electrodes, two on either side of the nose and one of the nose bridge. This will be battery powered. The expected ...
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Which lead is the output when 3 lead ECG system is used?
I am using ECG signal conditioning chip called AD8232. It takes 3 inputs, namely, right arm (RA), left arm (LA) and Right leg (RL) & gives one analog output as the ECG signal. According to ...
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Would grounded conductors placed on skin prevent signals from reaching a shielded body part?
Here is the scenario:
You are in an environment where there are sources of EM signals that your body will pick up as though it were an antenna via capacitive coupling, i.e. what happens with the 50/...
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Any theoretical reference for empirical equation for estimating oxygen saturation (% SpO2 = 110 - 25*R)? [closed]
The empirical equation used to estimate % SpO2 is based on the observation that the ratio of the red and infrared light absorbed by arterial blood (represented by R in the equation) varies linearly ...
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How to eliminate the noise of this circuit?
I've built the following circuit on a PCB with reference to a TI's solution.
I changed the gain of the INA to 10 and the gain of the A3 stage to 40. I also changed the cut-off frequency of the A4 ...
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Why am I barely able to read the voltage changes with this circuit?
I'm using this EMG sensor to measure the EMG signal from my bicep. However, I can barely read the voltage change from an oscilloscope when my muscle contracts - the output is a horizontal line of 1.5V ...
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What is the reference voltage of Vin- and Vin+ in this circuit?
I'm trying to make a PCB board to measure Electrocardiogram (ECG) signal. I have some doubts about the DC offset of the 2 input signals (\$V_{IN-}\$, \$V_{IN+}\$) with reference to analog ground. I ...
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Is one RLD electrode enough for multichannel ECG acquisition system?
I am trying to design the multichannel ECG measuring device. My device has to acquire 3 signals at the same time. I have to use 6 electrodes to be able to measure those signals. My problem is each ...
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How does a driven right leg work?
A driven right leg (DRL) circuit is often added to a biopotential amplifier to reduce the common mode voltage (i.e. to increase the common mode rejection ratio, CMRR).
A basic form of biopotential ...
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Is it valid to use transistors to route signals through the circuit?
I'm working on an ECG/EMG circuit and instead of duplicating the input, I've used transistors to route the signal to a specific in-amp depending on the user's selection. This is what I came up with:
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How does carbon paste (graphite) interact with other conductors?
I am running a half-cell battery configuration. I am using carbon paste (graphite) as a trace (jumper) because my solution contains bio-materials and carbon is bio-friendly. The carbon paste is coated ...
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Can an oscilloscope be used as an EKG?
I was at my doctor's office and noticed an EKG machine that looked like a standard oscilloscope. In fact, its case was almost identical to my dual channel Tektonix 1104b. The main difference was that ...
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How to compute electric field between constantly changing potentials (LFP data)
I have a set of LFP (local field potential) data, which is basically the voltage of different points in the brain at different times. I would like to calculate the electric field at these points at ...
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Differential Square Current generator LTspice
I am trying to model a square wave differential current generator in LTSpice for MAX30001 IC, refer page 6 for the specs.
Specifications: Differential Square wave, Amplitude : 8 to 96 uApk and ...
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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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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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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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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 ...
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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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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 ...
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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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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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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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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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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 ...
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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 ...
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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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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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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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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 ...
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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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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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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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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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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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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 ...
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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 ...
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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 ...
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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 ...
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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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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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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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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 ...
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