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Questions tagged [medical]

For applications in the medical arena that will come in contact with a patient. In general these applications need to satisfy international standards such as IEC60601. These applications have stringent patient isolation constraints, capacitive leakage constraints, mode of failure constraints, and voltage or current limits that can impose considerable design limitations.

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EKG active filter designs with single power supply

This is my beginners attempt at designing a EKG. I have printed out the PCB and attached all components to it to test it out. What I have observed are the following: 1. The outputs Vout1 as well as ...
Evank800's user avatar
3 votes
0 answers
73 views

Difficulty in gaining Class II CE certification for an aluminium single-sided PCB

We have a product that consists of an aluminium single-sided PCB with micro-controller and LEDs soldered to the copper side. The PCBA is shaped so that it can be bent to fit over the scalp of the user ...
Ron Brown's user avatar
0 votes
1 answer
37 views

EFT on powersupply AC input

My system I use 110 V to 36 V power brick (medical grade), and having hybrid cable which takes this 36 V and Ethernet and goes to the system. I am testing the EFT as per 61000-4-4 (± 2 kV, 100 kHz ...
NICEGUY NICEGUY's user avatar
1 vote
0 answers
69 views

Medical device on patient's bed..Cannot earth the Chassis..How to provide ESD protection?

We are developing a medical device, which will sit on patient's bed. So, the medical device chassis can't be connected to earth. The powersupply of the device is isolated (2MOPP and 2 MOOP), medical ...
NICEGUY NICEGUY's user avatar
0 votes
2 answers
109 views

Can I use USB C 3.2 Gen2 connector for power and data for a medical application?

My class 3 medical system uses 36V (~100W), 100Mbps ethernet for communication. I am planning to use USB 3.2 gen2 connector and cables to simplify my cabling in the system, and to have EMC shielding ...
NICEGUY NICEGUY's user avatar
0 votes
1 answer
140 views

The amplification factor of the EMG circuit did not meet expectations

I've recently embarked on a project to create a DIY EMG system and have been using Multisim for simulation purposes before finalizing the PCB design. Attached is an image of my EMG circuit. In this ...
Chen Yang's user avatar
0 votes
3 answers
379 views

Safety of grounded and isolated AC in medical systems

Introduction I try to make more sense of safety and reliability of grounded and isolated electricity. I divided the problem into 3 stages: Power-transmission line Household electricity Electrical ...
M lab's user avatar
  • 1,424
0 votes
1 answer
82 views

How do the input current bias and the driven ground circuits in OpenBCI Ganglion work?

I am trying to understand how the OpenBCI Ganglion board works, but I can't figure out how these two sub-circuits work. I'm sorry I'm not too familiar with op-amps.
AlexanderCar's user avatar
9 votes
3 answers
758 views

Are rechargeable li-ion considered primary batteries if charging is not available on the device?

We are designing a one time use medical device which we would like to power using a li-ion pack that would be charged only once at the time of manufacture. For the purposes of compliance (IEC 60601) ...
Isabella Lindquist's user avatar
1 vote
2 answers
328 views

What does 2xMOPP really mean

I am a student and I am designing a medical device that has a type CF applied part. I know the specifications that the applied part must comply (4kV of insulation, 8mm of creepage, <10μA patient ...
fox_rafa's user avatar
2 votes
0 answers
37 views

What is the ideal wireless protocol that is best suited for wireless nerve impulse transmission? [closed]

I am working to develop a way to transmit nerve impulses wirelessly (or wired) past a break in the spinal cord. What would be the ideal protocol to effectively relay the signal? Even if the device was ...
Lunatic Radio's user avatar
16 votes
3 answers
3k views

How is a mains-connected medical device made safe against electrocuting me?

I am in physical therapy now. Some of the devices are connected to wall power, and used for muscle electrostimulation. The patient information states that no single malfunction can connect me to 230V, ...
Mołot's user avatar
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2 votes
0 answers
111 views

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 ...
Jahir hussain's user avatar
0 votes
2 answers
90 views

What is the safest way to control another circuit?

From my custom board with an MCU I need to connect to an Interlock Pin of another circuit. I have a lot of options, but I don't know what is better. Using an optocoupler, but I'm afraid the output ...
Knowledge's user avatar
  • 443
0 votes
0 answers
112 views

Difficulties with multiplexing PPG signal in pulse oximeter

I've designed pulse oximeter circuit. When one LED lights continuously, I got perfect PPG (Photoplethysmogram) signal. Then I measure PPG while blinking LEDS, like that: I got stuck. There is no ...
Dom.in's user avatar
  • 21
3 votes
1 answer
92 views

Help with finding the type of output for a mems mircophone

I am using this MEMS microphone for a stethoscope project. The data sheet recommends the following interface circuit. I can't seem to find where it states specifically that it is a differential output ...
EcksDeECksdeee's user avatar
4 votes
2 answers
923 views

How do medical SMPS achieve lower Earth leakage compared to "regular" AC-DC SMPS?

When using a "regular" (i.e. not medical grade) AC-DC isolated SMPS in the following fashion, a strong mains common-mode voltage is created on the DC side due to - I believe - the stray ...
tobalt's user avatar
  • 22.5k
1 vote
1 answer
628 views

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 ...
Jack Black's user avatar
0 votes
1 answer
279 views

How to convert the outputs from the MAX30003 and/or AD8232 ECG modules to millivolts (mV)

I have been working with the MAX30003 and AD8232 ECG modules for a while now and I am trying to figure out what the raw outputs from both modules correlate to. I cannot seem to find any information ...
Dev_Engineering_'s user avatar
3 votes
3 answers
1k views

Difference between a normal tactile switch/pushbutton and a detection switch/pushbutton

What is the general difference between a normal tactile switch/push button and a detection switch/push button? I have heard that if in an application, for example, a pushbutton has to be pressed for a ...
Lyoner's user avatar
  • 339
2 votes
1 answer
191 views

AC filtering: Medical vs Standard Version

I am looking at that Schurter's AC power entry modules to choose a AC filtering module and at page 5 I noticed the differences between Standard version and Medical version: Their only difference is ...
Christianidis Vasilis's user avatar
0 votes
1 answer
200 views

Risk of getting shocked by ECG leads? [closed]

I have recently come into possession of a GE patient monitor (Eagle 4000) which looks structurally sound, probably decommissioned because of its age. It seems to work without a hiccup but I remembered ...
transforman's user avatar
1 vote
0 answers
76 views

Is there a standard equivalent to automotive standard AEC-Q200 for the medical sector?

I want to ensure components of high integrity characteristics are utilised in a design by a third party. In the automotive sector AEC-Q200 can be stipulated, e.g. (https://www.digikey.com/en/product-...
SeanJ's user avatar
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0 votes
1 answer
118 views

What is a good SNR for a medical device like a pulse oximeter?

What is a good SNR for a medical device like a pulse oximeter? Is there a U.S. Federal standard for this? Thanks!
meh's user avatar
  • 119
2 votes
1 answer
252 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 ...
Alex's user avatar
  • 121
9 votes
2 answers
591 views

Medical electronic devices quality

Is there a special grade for electronic components made to be used in medical devices such as life support systems? I have read in most data sheets that "this product is not to be used in life support ...
User's user avatar
  • 849
0 votes
2 answers
165 views

Pressure sensor without using MEMS chips [closed]

I'd like to figure out how to make a pressure sensor for very low cost (essentially disposable), mass produced piece of medical equipment. The problem: this can't use any parts which aren't already ...
Alex I's user avatar
  • 3,501
-1 votes
1 answer
138 views

Developing a Medical Product Using AliExpress Modules

We are developing a medical product and we are using some modules that we got from AliExpress (www.aliexpress.com). They are really cheap and gave us the same results with the modules which we made ...
user129710's user avatar
6 votes
1 answer
204 views

What type of ultrasonic transducers are used in medical ultrasound devices?

When I search on DigiKey for ultrasonic transducers, all I get back is the circular transducers that are sold for the various DIY projects. i.e. the picture below: However, the "medical" ultrasound ...
KingsInnerSoul's user avatar
2 votes
2 answers
505 views

SMPS electrical noise issue

1I'm using class 2 medical graded SMPS in our device. So earth connection not recommended. When connecting SMPS to load (contains capacitive touch LCD), touch function is affected by SMPS noise. When ...
Boopathi's user avatar
8 votes
5 answers
3k 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 ...
DodZi's user avatar
  • 115
2 votes
2 answers
322 views

Circuit for high-voltage pulses using Raspberry Pi PWM to drive a piezoelectric actuator

I am trying to engineer a device to separate red blood cells from blood plasma in 100mm x 1mm capillary tubes using the Raspberry Pi GPIO pin PWM feature and a piezoelectric actuator. The pulses ...
Vincent D.'s user avatar
0 votes
2 answers
244 views

ECG electric design: 1 and 3 op-amp designs from a safety point of view

During the design of an ECG using an instrumentation and a differential amplifier, we can across this question: Comparing the one and three op-amp designs from a safety point of view: of the two ...
FFLS's user avatar
  • 115
5 votes
2 answers
2k views

Using optocouplers at the end of a twisted pair

I am designing a dumb "isolation box" that is to sit between a computer and medical data acquisition equipment. The purpose of this box is to inject power and to provide communications and digital ...
Edgar Brown's user avatar
  • 8,476
1 vote
2 answers
520 views

Double ethernet magnetics for a passive medical application

I am designing medical data acquisition equipment that requires moderately fast data transfer. As part of the design we are using a custom 100BASE-T PoE architecture (and cabling) to the data ...
Edgar Brown's user avatar
  • 8,476
0 votes
2 answers
196 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 ...
Nishant Kathpal's user avatar
1 vote
0 answers
76 views

Medium Power Charge Pumps

I'm working on an MRI research project where I need to power my device with a single BNC cable. Internally my device needs 15V, -8.5V, 5V, 3.3V and 1.2V supplies. The 15V, -8.5V and 1.2V only need ...
dstpk's user avatar
  • 11
0 votes
2 answers
189 views

How to measure body temprature and HBR with just one IR transmitter and receiver

I want to measure body temperature and heartbeat rate only with a IR receiver and transmitter. How could I do that? Is it an accurate method? Or I have to use IR temperature sensor for this.
Panda's user avatar
  • 222
0 votes
1 answer
349 views

Power supplies with medical safety approval

Regarding the data sheet of this SMPS power supply. In the first page it says: 2 x MOPP Medical safety according to AAMI/ANSI ES 60601-1:2005(R) and IEC/EN 60601-1 3rd edition Then I googled to ...
user16307's user avatar
  • 12.2k
7 votes
2 answers
1k views

Designing single fault safety into class I device

I'm trying to wrap my head around safety standards for electrical equipment. My device is medical, so for me section 8 of IEC60601-1 is what really matters to me, but it's kind of my understanding ...
deltamac's user avatar
  • 131
12 votes
10 answers
4k views

Is it practical for firmware to be uniquely identified in production

Are there systems available in large scale manufacturing that allow a unique serial number to be programmed into the firmware or some free memory space for each PCB that comes through? I've found ...
Lukeyb's user avatar
  • 223
0 votes
1 answer
325 views

Ambient Light cancellation on Pulse Oximeter

I'm trying to build a pulse oximeter using TSL2305 LTF sensor and 2 LEDs(Red and IR). The desired graph expected from the light are plotted correct but I want to know whether there should be any ...
Arun Joe Cheriyan's user avatar
0 votes
1 answer
433 views

Defibrillator energy?

Just been reading this where this statement is made: If the patient is in Ventricular tachycardia (VT) or ventricular fibrillation (VF) on the monitor, immediately apply the pads and shock the ...
Dirk Bruere's user avatar
3 votes
1 answer
231 views

Patient Connection Radiated Emissions problem

The company I am working for is developing a patient-connected device intended to deliver Functional Electrical Stimulation to a connected user. We are currently struggling to pass the radiated ...
John Taylor's user avatar
1 vote
1 answer
100 views

Why do I need to keep Led drive and photodiode ADC supplies and traces separate in a pulse oximeter design

I've seen a couple of application notes recommend keeping led drive supply and ADC supplies separate. To me it seems that since the LED will illuminate the photodiode that ADC is reading anyway, ...
pkuhar's user avatar
  • 473
4 votes
2 answers
162 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 ...
smeeb's user avatar
  • 797
1 vote
2 answers
2k views

How is this EEG circuit amplifying and filtering input correctly?

Several weeks ago I posted several|questions about a DIY EEG reader that I found on Instructables. To my surprise, it appears to actually be a fairly well-designed circuit. The main stages of this ...
smeeb's user avatar
  • 797
2 votes
1 answer
435 views

How do I choose a cable /cord, connected to mains part, that is compliant with IEC 60601-1 3rd ed.?

IEC 60601-1 is a standard for medical devices. It describes which are the requirements for the Means of Operator Protection and Means of Patient Protection, the current leakages and so on. I don't ...
user36531's user avatar
1 vote
2 answers
342 views

To what extent does an ADC solve noise along an analog circuit?

Please note: Although this question involves EEG, I don't expect anyone here to be knowledgeable in this area! This is a simple electronics question! I'm trying to understand the circuitry devised in ...
smeeb's user avatar
  • 797
0 votes
3 answers
210 views

Surface-Mount Prototyping (AXL 335 & SFH 7050)

I'm working on a senior project and I'm having some trouble prototyping with surface mount components. I know you can find SMT adapters out there for most SMT chips and components, but I've been ...
moonman676's user avatar