Wireless, hand held monitoring device for Medical device application

What sort of accuracy is required ?

For the length of stroke, have you considered low cost ultrasonic or IR measurement sensors ?

There are also the likes of the linear magnetic/optical tape based encoder sensors.

What sort of accuracy is required ?

For the length of stroke, have you considered low cost ultrasonic or IR measurement sensors ?

There are also the likes of the linear magnetic/optical tape based encoder sensors.

Ah, like they use on digital micrometers or when you retrofit a digital readout to your lathe! Good idea and not prohibitively expensive.

Yes. I think some computer printers used to use them for measuring the position of the print head carriage, so may be a cheap source for experimentation purposes.

Of course accuracy is always important but it's not being used on a nuclear triggering device if you know what i mean.  I would think (+-) 3 or 4 percent of a the actual distance of the stroke s or weight/pressure being applied buy the linear actuator would be close enough.  I would assume the trade off for more exact numbers would be higher prices for these components like most equipment of this sort?  I have not consider ultrasonic or low cost IR measurement sensors or linear magnetic/optical tape based encoder sensors.  But i am completely open minded to any and all of your suggestions or insights.  Of course every once in a while a particular piece of equipment comes along that works perfect and is most affordable which in a sense is largely a part of this whole theory/concept of my simple spinal decompression chair.  It's simple, but most effective bringing almost instant relief to the many maladies of compressed vertebrae and discs. Perfect for proactive back pain suffers who want to be able to treat themselves in the comfort and convenience of their own home without drugs, invasive medical operations, travel time, expense, etc.  I have used inversion table for years and nothing is more simple than these devices.  However, hanging upside down has many negative and potential disastrous affects on the body.  The ankles are not designed to support all your weight and it only best at easing the lower 5 vertebrae and disc in the lumber area.  It has almost zero affect on the other 12 discs and vertebrae in the Thoracic area and 6 more in the Cervical Areas.  Plus the ability to be able to torque one's own spinal column while the head is held in a firm position easily allows the adjustment of these areas very similar ,if not identical or superior, to chiropractic techniques.

I've used both now for over a year and clearly the Decompression Chair has it's major benefits for the mid to upper spinal column over these very popular Inversion Tables.  Having a simple, hand held wireless (bluetooth) device that could monitor these parameters of length, pressure and time would be most attractive to consumers or professionals and clearly an essential requirement, don't you think? 

Thanks again for your sage suggestions and insight.

jack ellenberger

Thank you again, I'll try to find a source for these and purchase a few. 

jack e.

Yes, digital micrometers made in China are really dirt cheap but i don't want the least inexpensive of course but i did buy one of these cheap micrometers and it seems to work well but the battery did not last...probably a cheap battery that comes with the unit? I'm sure a better battery would make a big difference.  I'm glad you got the pics and the drawings and they lent some better insight to my needs and wishes.   I built all the prototypes in my garage and use fairly common components readily available.

jack e.

Plus or minus 3 or 4 percent should be more than enough.  No but i'm certainly willing to test them out...any links or websites or do you sell these devices??

Thank you.

jack ellenberger

The most important detail of this device would be the capability to monitor pressure (traction) followed by duration (fairly easy) and lastly stroke length.  I would be pleased with the first two readouts for the sake of keeping it as simple and affordable as possible.

jack e.

IR sensor from Sharp which has a working range of around 10cm to 80cm

https://www.adafruit.com/product/164

These Maxbotix ultrasonic rangefinders have a precision of around 1mm with a working range from 30cm

https://www.adafruit.com/product/983

Time of Flight laser distance sensors

https://www.adafruit.com/product/3316

Magnetic linear encoder

https://www.machine-dro.co.uk/hobby-digital-readout-systems/magnetic-encoders.html

Optical linear encoder

https://www.machine-dro.co.uk/hobby-digital-readout-systems/optical-encoders.html

Linear potentiometer

https://www.reichelt.com/de/en/Position-Sensors/2/index.html?ACTION=2&LA=3&GROUP=B68&GROUPID=6681&START=0&OFFSET=16&SHOW…