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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29
votes
6answers
12k views

Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV ...
14
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4answers
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 ...
14
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8answers
3k views

RnD on an EEG, Help required, what op-amp?

this is my first post, and I need some help/advice finding the right integrated circuits. I'll start by describing the project background a bit. I've received a fellowship to develop an open source ...
8
votes
3answers
25k views

50hz noise removal from ECG power supply

We are currently working on a bio medical project that is an ECG machine.There is a problem that we are unable to solve on software side is the removal of 50 Hz noise. Now we are trying to remove 50 ...
8
votes
1answer
3k views

Patient protection resistors in the biopotential amplifiers

In biopotential amplifiers like ECG amplifier, I often see protection resistors (around 100kohm) between electrode and the input of instrumentation amplifier or ECG amplifiers like ADS1298. I ...
8
votes
5answers
3k views

Detect electrical signals from plants

My daughter wants to do a science fair experiment that involves reading the electrical signals in plants, but the cost of a multi voltmeter with data logging is very high. Can anyone suggest a setup ...
7
votes
4answers
12k views

Optical heart rate sensor vs bioimpedance sensor?

I didn't know a better place to ask this, so here it goes. For activity trackers, Fitbit has the Charge HR with an optical heart rate monitor, while Jawbone has the UP3 with a bioimpedance sensor for ...
6
votes
5answers
870 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 ...
6
votes
3answers
398 views

60Hz “click” or clipping noise when differential amplifier is surrounded by salt water

I am a graduate student attempting to take electrophysiology recordings from a lobster under water. In the current set up I am using, two differential amplifier boards are attached the the lobster's ...
6
votes
2answers
1k views

Does an electrocardiography recorder put current/voltage on its electrodes?

(I do hope my question is not off-topic) Currently learning about ECG recorders (Our 7-months old daughter has to have one during her sleep), I wonder whether this is a pure "passive" measuring ...
6
votes
1answer
2k views

ECG: gain of right leg drive?

I am trying to build a simple ECG circuit. I designed the circuit based on multiple ideas from the internet and the parts (INA118P) available. What I do not exactly understand is how much the gain of ...
5
votes
5answers
1k views

User safety for battery powerd device against misuse of power supply

I want to design a safety circuit for a battery powered device which measures human body impedance. It is intended to be powered only by an external battery pack (5V) via a USB cable. But I want to ...
5
votes
4answers
1k 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 ...
5
votes
2answers
533 views

Is there an advantage to process EEG data as analog (vs digitized) signals?

Please note: Although this question mentions an electronic circuit depicting an EEG, I believe this is purely a bio-electrical question that is appropriate for this site, and should be answered by any ...
4
votes
1answer
1k views

gain with no side effects

I want to see a signal (5-25 microvolts | 1-35HZ) on my computer.but I dont know electronics so I just have one question: I need to amplify THE signal to reach <...
4
votes
2answers
1k 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 ...
4
votes
2answers
119 views

Circuit Testing, Verification & Certification Standards for Biomedical Devices

Please note: I would have posted this question on HealthIT.SE but they are apparently now closed for business, and I believe this site is the next most appropriate place to ask this. I believe this ...
4
votes
3answers
1k views

DIY EOG (Electrooculography) Circuitry Dangers?

I wanted to try to build my own EOG filter and amplifier circuit. I've found many online sources that use an instrumentation amplifier, high pass and low pass filters, and additional amplifiers on the ...
4
votes
3answers
2k views

How to set up an experiement to measure SNR for an EEG amplifier?

I have built an EEG amplifier with gain of 2000 and bandwith at 1~40Hz. I use an Instrument Amplifier for pre-Amp and a non-inverting opamp as post-amp and finally bandlimit at 40Hz using a 4th-order ...
4
votes
1answer
2k views

Is it possible to measure the voltage produced in heart

I learnt from my high school biology that human heart will produce about 1mV from the sinoatrial node.(voltage will vary like the graph in ECG test).Is it possible to measure the voltage with any ...
4
votes
1answer
376 views

Questions about Dry EEG electrode interfacing circuit

I have finished reading a paper about developing an interfacing circuit for Dry EEG electrodes and there is a few points that I couldn't understand. To mask the diode’s parasitic capacitance and ...
3
votes
1answer
953 views

Bioelectrical Body Impedance Analysis?

On what principle Bioelectrical Body Impedance Analyzer works? I thought about this many times, and I wanted to know is there really a way to precisely measure all those body parameters with this ...
3
votes
3answers
3k views

Amplify Microvolts up to Volts

I'm trying to create completely DIY EMG. As many of you may know, I will be dealing with microvolt inputs. I know that op amps amplify voltage, but I am wondering if I can somehow get a 1,000,000x ...
3
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3answers
3k views

sEMG with ADS1299 from TI

What else besides an ADS1299 from TI and a 32bit microcontroller (like Teensy or Electric Imp) would I need to get an sEMG signal? The ADS1299 is a "low-noise, 8-Channel, 24-Bit analog front-end for ...
3
votes
1answer
673 views

What are some techniques to lower noise on a mixed-signal analog-to-digital converter board?

I'm building a 24-bit ADC board for Arduino that can sense microvolts (biological signals). What are some good techniques to lower the noise that will negatively affect the ADC resolution? What I've ...
3
votes
2answers
633 views

Efficient spike detecting Microprocessor or DSP architecture

I am looking for microcontroller or DSP (or its architectures) which are efficient in terms of power as well as performance in detecting spikes. I want to run an algorithm which detects spikes and ...
2
votes
3answers
494 views

Wireless EEG electrode design

Currently, all 'wireless' EEG systems acquire signals from electrodes which are wired to an amplifier, a filter, a digitizer and then finally a wireless module. I want to design a system that's ...
2
votes
2answers
1k views

What can ECG DC level be?

In ECG signal, to what DC level should i expect? Can it be 3V, at least from time to time? Alternatively, what would be decent input voltage range for the instrumental amplifier for ECG stage?
2
votes
2answers
1k views

How can EEG electrodes pick up EMG signals and still function?

EMG signal is the signal generated by muscle flex. EEG electrodes is the scalp potential generated by neuron firing. EEG is on the order of micro Volts whereas EMG is on the order of mili Volts, this ...
2
votes
4answers
1k views

sense movement of muscles via electronic signals

I'd like to sense when a certain muscle is contracting or releasing, for instance the movement of one finger over another. Is there any existing work to do this with sensors / arduino / galvanic ...
2
votes
2answers
869 views

Doing FFT of electroencephalogram signal at 200Hz - what window size to use?

I got a brainwave EEG(ElectroEncephaloGram) sensor that is continuously sending data over to my program at about 200 data points per second. Can someone suggest what window/bin size I should be using ...
2
votes
2answers
48 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 ...
2
votes
1answer
1k views

How can I make an LED glow by touching it with my finger?

I can make an LED glow very dimly in all 4 following circuits. The voltage source in the circuits is the output of an AC to DC converter fed into a breadboard. Also, one end of the voltage source is ...
2
votes
1answer
337 views

Building an instrumentation amplifier

I am trying to develop a system for bioimpedance measurement. I will use a frequency equivalent to 50KHz, using this project to support me. The project uses an instrumentation amplifier. In my city ...
2
votes
1answer
710 views

How does the Bias Drive in TI ADS1299 help in noise reduction?

I'm bit of a noob in electronics so please pardon me if this question is too basic. I would like to clearly understand how the signal from the bias drive electrode can help in noise reduction, ...
2
votes
1answer
56 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 ...
2
votes
1answer
401 views

AD8222 single supply EMG

I am working with the AD8222 dual package instrumentation amplifier from Analog Devices. I want to build a compact EMG system so I am trying to use this chip since there are not a lot of dual IAs on ...
2
votes
2answers
416 views

Electronic sensor for monitoring photosynthesis

I have to develop a sensor that can detect photosynthesis. So when the plants are exposed to sun I should get an indication that photosynthesis is happening inside the leaves. I found many products ...
2
votes
1answer
2k views

Arduino - Cannot get ECG readings from heart, but I do when I poke at the leads

I have a minor issue with my ECG. When I poke at the leads, I get a reading. But when I hold the leads or place it near my heart, I don't get anything. I'm pretty sure this is hardware related, but ...
2
votes
1answer
146 views

ADS192R respiration rate detection

In SBAA181 - Respiration Rate Measurement Based on Impedance Pneumography (page 8/11), what is the purpose of having potential divider of 10ME (R1=R2)? the reference of these resistors are R84,R85,...
2
votes
2answers
115 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 ...
2
votes
0answers
1k views

How to find the resonant frequency of a human body?

I've read that the human body has resonant frequencies somewhere around 50MHz. I also think it would be interesting to look for values in other ranges like 10-100 kHz. I'm wondering how to build a ...
1
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2answers
581 views

Hardware to Detect EMG or Skin Resistance

I have been given assignment to design a device that can detect emg signal of Skin Resistance change while moving fingers. actually i need to track finger movements using some hardware containing ...
1
vote
1answer
659 views

How can I detect brain waves

I want to build some type of electrical circuit to detect alpha, beta , theta etc. waves from the brain and maybe even show the frequency in hertz . Or at first, generate a higher power wave for my ...
1
vote
1answer
149 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 ...
1
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3answers
166 views

Biological 'Black Box' - how to test for underlying logic?

Firstly, I am a neuroscientist - so bear with me! I have a collection of connected brain cells (network) and a means of recording the electrical output, as well as manipulating the input to the ...
1
vote
1answer
2k views

Noise reduction in physiological measurements (EEG/ECG) [duplicate]

I am building a hobby EEG and I am interested in quantifying how effective are the various noise reduction techniques. The basic circuit would be two electrodes going to an instrumentation amplifier. ...
1
vote
2answers
93 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 ...
1
vote
1answer
300 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?
1
vote
1answer
58 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 ...