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.
40
questions
16
votes
3
answers
2k
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, ...
- 639
2
votes
0
answers
71
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 ...
0
votes
2
answers
84
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 ...
- 391
0
votes
0
answers
62
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 ...
- 21
3
votes
1
answer
69
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 ...
4
votes
2
answers
734
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 ...
- 18.8k
1
vote
1
answer
209
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 ...
- 177
0
votes
1
answer
197
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 ...
3
votes
3
answers
677
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 ...
- 329
2
votes
1
answer
141
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 ...
- 2,769
0
votes
1
answer
105
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 ...
- 13
1
vote
0
answers
58
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-...
- 897
0
votes
1
answer
104
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!
- 119
1
vote
1
answer
170
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 ...
- 111
9
votes
2
answers
586
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 ...
- 839
0
votes
2
answers
149
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 ...
- 3,341
-1
votes
1
answer
129
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 ...
- 19
6
votes
1
answer
184
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 ...
- 829
2
votes
2
answers
395
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 ...
- 21
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 ...
- 115
2
votes
2
answers
265
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 ...
- 21
0
votes
2
answers
238
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 ...
- 115
5
votes
2
answers
1k
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 ...
- 8,366
1
vote
2
answers
433
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 ...
- 8,366
0
votes
2
answers
188
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 ...
1
vote
0
answers
73
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 ...
- 11
0
votes
2
answers
180
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.
- 222
0
votes
1
answer
335
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 ...
- 11.8k
6
votes
2
answers
975
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 ...
- 121
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 ...
- 223
0
votes
1
answer
300
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 ...
0
votes
1
answer
395
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 ...
- 13.4k
3
votes
1
answer
218
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 ...
- 61
1
vote
1
answer
98
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, ...
- 473
4
votes
2
answers
150
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 ...
- 787
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 ...
- 787
2
votes
1
answer
367
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 ...
- 21
1
vote
2
answers
293
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 ...
- 787
0
votes
3
answers
203
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 ...
3
votes
1
answer
814
views
Make an electronic Stethoscope
I've seen some kind of electronic stethoscope that can capture heart beat rate and filter it with so many other features.
Main oscope of my questoin is about capturing heart sound. There is many ways ...
- 510