electromedical devices

[nacho1]

Hi mi name is nacho I'm from Argentina. I work in a hospital, in the clinic engenier deparment.
If anyone want help or have some questinons about electromedical devices, please ask me.
I've searching for forums to discuss these topics and I dont found anything.
Thanks

[Malcolm]

Hi nacho1,

Could you post some  medical devices electronics schematics/service manuals :-
(a) Ultrasonic Therapy Devices
(b) Diathermy Decives
(c) X-ray Machines,etc.etc

Thankx

[nacho1]

Malcom:
could you be more specific. because my hospital isn't at the top of medical technology.
we still have some devices from the 90 working. Schematics for a particular equipment
are hard to find, but i might help you tell me more about your problem or what you want to do.

[qwerty]

i've got something to ask , i want to build a heart rate monitor using PPG (Photoplethysmography) and ECG from finger. what can u explain about this , how do i do it , is it possible to get a heart rate using from finger? is there any circuit design? thanks.

[nacho1]

qwerty

the Photoplethysmography, its widely used to messure the porcetn of Oxigen in the blood.
it uses an IR led an a red led centered arround 960 nm , and a photoreceptor.
the amount of energy recived is a functron of the absorption of CO2 in blood.
besides the amount of blood in a vein or artery changes when the heart pumps.
so you can take the heart rate measurin the interval of these pumpings

I dont known any medical intstrument that takes the ECG Signal Form the plethysmograph curve
always see the clasical instrumentation amplifier and the analog filters

[margo]

check out...http://www.ebme.co.uk/

[qwerty]

how about this circuit ? http://www.web-ee.com/Schematics/HeMon/HeMon.htm can anyone give some explanation about it ?

[nacho1]

in that project a red led and a photoresistor is used. As I said before, you senses the amout of blood when the heart beat. this variation is sensed by the resistor, then you adapt the level of signal using the lm358 an the pic counts the number of pulses, and then displays the number in the 7 segments.
if you see the picture in that web the yellow curve is the variation of the amount of blood, you pass this through a comparator and you have the blue curve an then you send it the pic.

 the only physiological parameter you can measure is pulse rate. but not ecg.

[pcapelo]

Hi nacho, thanks for your colaboration.

I am very interested in some specific topics like electrostimulation and iontophoresis.  In your hospital what kind of equipment use for that things?  If it is possible, can you attach a diagram of some electrostimulation equipment?

Thanks in advance

[solec]

Hi nacho1,

Is there any other method how to measure heart-rate except electrodes on the skin, measuring on the finger or microphone in the stetoscope? I have seen somewhere equipment, where were person holds contact in every hand...
Thanks in advance
solec

[simma]

Hi nacho1,

Is there any other method how to measure heart-rate except electrodes on the skin, measuring on the finger or microphone in the stetoscope? I have seen somewhere equipment, where were person holds contact in every hand...
Thanks in advance
solec

See http://www.sonsivri.com/forum/index.php?topic=10382.0

[nacho1]

Hi pcapelo i've built this circuit and works great. its a voltage to current converter.
in my test I inject a 10uA current to my arm, and then pickup with an ad620.
some results: below 10HZ and more than 1mA you can feel the stimulation,
over 1mA to 10mA the sensation increases. More than 10mA it's really painful.
If you increase the frecuency all these effects dissapears, but the current still circulating.
I´ve achieved 10uA @ 60khz that was  my goal, but you can try at other frecuencies and currents.


http://www.edn.com/index.asp?layout=article&articleid=CA321804

In the circuit I've replaced the transistors for a BC547 and BC557 if you don't found the 2N9019/2N4033.
unfortunateley we don't have any of these equipments or schematics.
I hope it help.


Solec You can mesuure heart rate in a lot of diferent ways.
1° ECG it's the best way because you are picking up the electrical signal from the heart.

2° SPO2 or Photoplethysmography. the disadvantage of this meteod is if the blood dont circulate
    with a good flow in the limb  its hard to take the  signal.

3° With NIBP (non invasive blood presure) or IBP (invasive blood presure) using a pressure transducer.
    In NIBP the mechanical hardware its a little complicated.
    You need a pump to inflate a cuff in the limb and depend of the position  and how tight you put the cuff.
    In IBP, its more complicated, because you need a pressure transducer in contact with the blood of the patient.

ECG, SPO2 and NIBP are non invasive method

 bye

[manoj]

hi,
can u help me to find remote sensor which can detect heart beats

[nacho1]

Manoj use this schematic as reference design. to pick an ecg waveform.
http://www.analog.com/library/analogDialogue/archives/37-11/ecg.html

or you can use Photoplethysmography to take pulse rate
http://www.picotech.com/experiments/calculating_heart_rate/

after the AD620 or the lm358 you should see a peak corresponding to the beat of the heart.
then you can transmit this pulse via IR or RF or Bluetooth.

if you are asking for active sensor technologies I've heard is in developing, but nothing comercial yet.
bye

[ism_ibm]

I'm building High frequency high voltage resonant X-ray generator, rated at 15KW 100mA.
I need any books, papers or schematics about HF HV x-ray generators.
thanks in advance.

[oldvan]

I would be interested to know how a blood oxygen sensor circuit works and how it is callibrated, the kind with a small clamp type device that goes over finger.  I see the sensor itself is available on eBay, but would love to know how the pros interface with it.

[machine]

Hi, the sensor saturate oxygen then (SPO2) calibrated in other equipament measurement gas blood directly. Gasometer ( http://www.radiometer.com/). The sensor have two LED ( red and infrared ) and obvius photodiode. After test in vittro blood gas, the electronic circuit is calibrated for measure equal gasometer.

[ALLPIC]

hello all, I am basically BioMedical Engineer

SPO2 has 2 leds 1. Infraread and 2. Read light source and at receiving end we have Photodiode, basic principle is as Blood is read so that will absorve all read light so that lesser the read light received higher the O2 concentration simple as it is.. Infraread is basically used to detect Pulse count and will be used at Vesoconstration.

For BloodGas instrument that is Invasive methode so you need actual Blood sample. In regular methode for counting blood gas (02) you have membran and concetated matrial this membran will pass 02 Contain only and that will make reaction with Camical material that will cause voltage across referance sensor and O2 sensor

[Skippy]

Hello ALL,

What's the best design for a multi-channel ECG for measuring Lead I, II and III.
There are many approaches for the system, one IA with next stage for filtering and switching the leads with analog multiplexer. Other way is to put one IA for each differential lead, this results in 3 IA's plus 3 filter replicated HW.

Is there anyone who ever made a system like this one?

Regards,
Skippy

[andig]

Hi,

I have been a member for sometime but never seen this thread. An interesting contribution to this forum. I am trying to find information on the following equipment related to electrotherapy (physiotherapy).

1. 27MHz Shortwave Diathermy (Can't seem to find any solid state reference design)
2. I.F.T. (Interferential Therapy)
3. Ultrasound Pain Therapy (1Mhz or 3 MHz)
4. T.E.N.S (Transcutaneous Electrical Nerve Stimulation)

While I have built a combined device having 2,3 and 4 it was kind of reverse engineered from the products available in the Indian Market. I studied the waveform and kinda generated them using a dsPIC. Unless I have more information I just cannot commercialize the product. Since it is a medical equipment. If there are sources of service manual of professional products for a price, I am interested.

Any help would be much appreciated.