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  • Author Author: jw0752
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Power Straw

jw0752

For several years my Mom has been in a Nursing Home with Parkinson's disease. As she has lost function of her muscles I have attempted to use technology to assist her. I have posted a couple of my attempts to assist her in my Blog on E-14.

 

https://www.element14.com/community/people/jw0752/blog/2015/07/07/hacking-a-lift-chair

 

https://www.element14.com/community/people/jw0752/blog/2016/01/15/building-an-led-amplifier-for-mom

 

Recently on her bad days she has been too weak to draw the thickened water she has to drink up a straw. This causes her to become dehydrated and quickly affects her health. She is very stubborn and will not allow herself to be fed by other than by herself. To help her in the days that she is too weak to drink through a straw  I have constructed this little device to assist her. I call it a Power Straw. It is very light on electronics so perhaps it does not have much application to our electronics site but since I had published previous projects I though a few of the guys would be interested.

 

Here is a schematic of the project:

 

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I began the project by collecting a variety of potential components. My Goal was to draw her thickened water from a reservoir and pump it up a line and into her mouth. She is accustomed to using a push button call switch when she needs help from an attendant so I decided to use a very similar switch to actuate the pump.

 

The water line would run axially with the switch and its wiring. The switch could be held in her hand and the water feed line would continue past the switch by about 4 inches.

 

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Picture of Hand Switch

 

I decided to try a small 12 volt water pump, that is usually used in small fountains, to pump the water from the reservoir.

 

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Picture of Pump in the Reservoir

 

My first prototype did not include an in line solenoid. This created a problem if the cord accidentally fell to the floor as gravity would siphon the water from the reservoir and create a big mess on the floor. My final prototype needed a solenoid.

 

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Solenoid Picture

 

Since space and weight were not a particular problem I decided to use two 6 volt 4.5 Ahr Lead Acid Gel Cells for the batteries.

 

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Battery Picture

 

A small Volt Meter circuit was incorporated in the control box so I could check the level of the battery and recharge it when needed.

 

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Control Box Picture

 

The control box is very simple with the Volt Meter and a momentary switch to activate it, a single P Channel MOSFET, Jacks for: Batteries, Charger, Pump, Solenoid, and actuation switch.

 

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Pictures on inside the Control Box

 

The Reservoir is an lightly insulated hospital drinking cup that I brought home after a past overnight adventure.

 

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Picture of the Reservoir.

 

Here is a picture of the finished project before I took it to Mom's room and nylon strapped it to the back of her wheel chair.

 

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Picture of completed assembly

 

I can see room for many improvements. The parts that I ordered and received did not meet my imagined specifications. For example the pump could have a little more power and the solenoid draws too much current. While the batteries will be heavy enough to deal with the present solenoid, ideally, I should be able to find one that uses 200 mA or less instead of the current 400+ mA. I have made the reservoir and hand cord easy to disassemble for cleaning but improvements can be made. The plugs that were used on the pump and the solenoid were not polarized. While this will not affect the solenoid it is important the the pump spin in the correct direction for maximum efficiency. I have marked the non-polarized plugs but someone other than me might miss this detail. For the time being however Mom is happy and after the newness wears off she too will have some good suggestions for her sonny boy on how he can make it better.

Parents

  • Here is the next iteration of the prototype using a peristaltic pump.

     

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    The first thing to note is that the reservoir holder has been changed so that it will accommodate the standard drinking cup that is used in Mom's nursing home. Rather than messing with pouring the thickened water that she has to drink into a separate reservoir all the staff has to do is replace one cup with another and insert the red hose into the straw hole. I mentioned thickened water. I never realized this but if one is not able to swallow properly water of regular consistency can pose a greater danger of choking. For this reason they give Mom a special thickened water that is easier to swallow.

     

    Here is a detail picture of the cup holder:

     

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    The red hose from the cup goes to the inlet of the peristaltic pump. The pump itself is controlled by a variable pulse width modulation generator in the control box. I was very pleased with the small peristaltic pump as it is capable of moving 75 milliliter of the thickened water per minute when the pump is running at 12 volts. Since the control box (See Red Capped Knob on top of the control) allows me to control the PWM 0% to 100% I can reduce the output of the pump as needed so as not to over run Mom's ability to swallow. Here is a detail of the peristaltic pump and the manifold that I built to interface with the feed from the cup and the line to drinking tube.

     

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    One of the very pleasant surprises was that the peristaltic pump only drew 32  mA at the full 100 % PMW level. This is more than a magnitude reduction from the 500 mA + current needed for the first prototype. Current calculations suggest that the battery should be able to run the unit for a couple weeks at a time without recharging.  Since the Peristaltic pump pinches the line continuously there is also no need for a solenoid to prevent siphoning. Check out the ammeter reading for the pump.

     

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    For the fun of it I made a video of the pump in action. Check it out.

     

     

    The unit is now back attached to Mom's wheel chair and she has been using it for a day. We will be watching for other problems and opportunities to improve it in the coming days.

     

    John

  • in reply to jw0752

    Perfect fit for purpose, and well engineered.

     

    two possible points for future improvement:

    • Make the piece of hose that goes into the cup easily replaceable. Just like Mark mentioned, staff may knack that part of the device when frequently changing cups
    • maybe a small plastic cup filled with damping material mounted over the pump, to soften the motor noise.
Comment
  • in reply to jw0752

    Perfect fit for purpose, and well engineered.

     

    two possible points for future improvement:

    • Make the piece of hose that goes into the cup easily replaceable. Just like Mark mentioned, staff may knack that part of the device when frequently changing cups
    • maybe a small plastic cup filled with damping material mounted over the pump, to soften the motor noise.
Children
  • in reply to Jan Cumps

    Hi Jan,

    The red hose that goes into the cup is made of a biological resistant polyurathane and is very durable. You can pound on it with a hammer and not damage it yet it is flexible enough to be workable. I have attached it to the pump manifold with a twist connector called a luer lock which allows it to be easilly removed and cleaned. I put the bottom of the peristaltic pump inside some of the foam insulation that they use for covering 1 inch water pipes to keep in the heat or prevent them from sweating. I think your idea for an insulated cover is a great one and I will incorporate t at the next turn.

    John