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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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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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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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 ...
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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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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 ...
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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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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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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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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 ...
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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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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 ...
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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 ...
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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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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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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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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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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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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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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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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 ...
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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 ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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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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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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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 ...
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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 ...
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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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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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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 ...
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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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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 ...
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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)?!...
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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 ...
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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?