Questions tagged [biopotential]

Instrumentation related to the measurement of bioelectric phenomena from the living system, such as ECG, EEG, EMG, and galvanic skin response.

Filter by
Sorted by
Tagged with
-1 votes
1 answer
29 views

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 ...
user avatar
4 votes
2 answers
924 views

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 ...
user avatar
3 votes
2 answers
933 views

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: ...
user avatar
  • 161
0 votes
1 answer
63 views

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 ...
user avatar
25 votes
3 answers
5k views

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 ...
user avatar
  • 1,977
0 votes
0 answers
23 views

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 ...
user avatar
0 votes
1 answer
98 views

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 ...
user avatar
  • 121
3 votes
1 answer
126 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 ...
user avatar
  • 31
1 vote
3 answers
165 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-...
user avatar
1 vote
1 answer
89 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 ...
user avatar
  • 111
0 votes
1 answer
240 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 ...
user avatar
  • 467
0 votes
1 answer
279 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 ...
user avatar
1 vote
0 answers
40 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 ...
user avatar
0 votes
3 answers
205 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 ...
user avatar
  • 422
1 vote
3 answers
66 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 ...
user avatar
  • 103
0 votes
3 answers
45 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 ...
user avatar
1 vote
2 answers
317 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 ...
user avatar
  • 8,613
1 vote
1 answer
43 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 ...
user avatar
2 votes
2 answers
175 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 ...
user avatar
0 votes
0 answers
90 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 ...
user avatar
14 votes
4 answers
2k views

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 ...
user avatar
  • 8,613
1 vote
1 answer
206 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, ...
user avatar
8 votes
5 answers
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 ...
user avatar
  • 105
2 votes
1 answer
106 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 ...
user avatar
  • 129
1 vote
1 answer
265 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 ...
user avatar
1 vote
2 answers
187 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 ...
user avatar
  • 133
1 vote
2 answers
503 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 - ...
user avatar
  • 13
0 votes
1 answer
76 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.
user avatar
  • 1
-2 votes
1 answer
503 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 ...
user avatar
  • 479
0 votes
1 answer
3k 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 ...
user avatar
  • 1
0 votes
2 answers
169 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 ...
user avatar
4 votes
2 answers
411 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 ...
user avatar
  • 41
0 votes
0 answers
128 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 ...
user avatar
1 vote
1 answer
592 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?
user avatar
0 votes
0 answers
160 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)...
user avatar
1 vote
1 answer
257 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 ...
user avatar
0 votes
2 answers
120 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 ...
user avatar
0 votes
2 answers
322 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 ...
user avatar
0 votes
1 answer
90 views

Common Mode feedback in EEG systems

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 EEG signal. ...
user avatar
1 vote
1 answer
84 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 ...
user avatar
1 vote
1 answer
189 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 ...
user avatar
4 votes
2 answers
4k 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 ...
user avatar
  • 55
5 votes
4 answers
3k 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 ...
user avatar
0 votes
0 answers
52 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 ...
user avatar
  • 32
13 votes
3 answers
6k 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 ...
user avatar
  • 133
0 votes
0 answers
188 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 ...
user avatar
  • 339
1 vote
1 answer
203 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: ...
user avatar
  • 133
0 votes
0 answers
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 ...
user avatar
  • 323
-3 votes
1 answer
304 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 ...
user avatar
0 votes
2 answers
1k 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=...
user avatar