IV Heater

Description

A simple heater for preventing Hypothermia when administering IVs in the field.
Idea is:

Hardware:
Heating block is made from spent shell casings (found in abundance on the battle field/in conflict areas) cast into the desired shape using a 3D printed positive and casting sand.
Tube is layed down inside the groove and the lid is closed on top and locked in place.
PID controller is based on an Arduino Nano in the initial version, before a custom board is designed.
Power supply is meant as a DC input from a battery solar, probably solar charged.

Software:
Initial version is a PID controller.
Later, profiles for ramping up the temperature in steps when dealing with patients having a low core temperature can be added.

Project Logs

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Pondering heat transfer....
Henrik Sorensen • 06/06/2020 at 18:16 • 0 comments
So... was considering heat transfer...
Flat surfaces and tubing really sucks! Limited area for the heat to be transferred to from the block to the tubing. What are the options?
1. Wrapping the tubing around a block (or a cylinder) with a groove cut for it.
2. Same as #2 with a matching outer casing.
3. Submersing into a fluid.
#1 : Only about half of the tubing gets the heat transferred from the heater.
#2: Parts must match exactly in order not to damage the tubing. Also, makes the application of the heater much more difficult.
#3: Add a liquid to the handling, and thus more risks.
Prototype heating block begun
Henrik Sorensen • 06/05/2020 at 21:41 • 0 comments

Got the block for testing the heat transfer of the tubing made.
I need to figure out how to transfer the heat from the heater while still having around 1 m of tubing inside it and avoid liquids. The easiest way would be to make a cool form, put the the tubing inside a container, add e.g. water and heat it up.
This adds unwanted fluids and more issues regarding daily use. E.g. evaporation, possibility of shorts etc.
But, let's measure and see what happens
Electronics prototype done
Henrik Sorensen • 06/05/2020 at 21:36 • 0 comments

Today, the PCB got populated with the components. Actually turned out OK for a first time attempt on milling a PCB on my cheap mill.
Getting ready for writing some code for controlling the temperature
Brainstorming session...
Henrik Sorensen • 06/03/2020 at 20:35 • 0 comments

So... today, I got my gritty mittens on an IV kit (Braun Intrafix) (and a blood kit) in order to get a better view of the task at hand..
Initially, I wanted the system to handle both IV (such as saline) and blood, but the flow rates are of a concern to me. Even professional equipment rolls up about 1 m (!!!!) of tube in order to create enough heating surface to heat the liquid and they even struggle with the ambient cooling of the last length of tubing.
Further input was given from a nurse related to the daily use and problems. This lead me to redesign the heating block based on the specifications of the tubing:
Neutrapur:
Diameter: 4.1 mm
Max pressure : 2 bar (current solution is a gravity fed system, so this is not important)
Max temperature: 40 C
I had hoped on setting a higher temperature for compensating for the ambient temperature based on the thermal resistance of the tubing (adjusted by the software), but I'll have to limit the maximum temperature to below 40 C.

View all 4 project logs

Discussions

Josh Starnes wrote 06/17/2020 at 01:04

Interesting way to heat the iv, by chance are you keeping up with the time required and cost per unit?

Are you sure? yes | no

Henrik Sorensen wrote 06/17/2020 at 05:03

Project has been on hold for a few days (works takes up too much of ones leisure time ;-) )

Anyhoo, I currently work on 3 different designs all having pros and cons :

1st:

Heating block cast out of old casings featuring temperature regulation.

Pros: Good heat transfer. Good precision.

Cons: Casting takes time (casting + collecting materials)and is energy consuming. Requires electronic components.

2nd:

3D printed (or molded) plastic bobbin (currently last pictures of the gallery).

Pros: Good heat transfer. Good precision.

Cons: Requires electronic components and specialized, plastic components. Requires fluid.

3rd:

"Bastard" version of 2nd design but made entirely out of junk and old car parts.

Pros: Good heat transfer. Recycling materials. No electronics or specialized components. Extremely low cost.

Cons: Time consuming to manufacture. No precision within temperature control. Requires fluid. Cleaning of the junk is recommended.

1st and 2nd designs have been tested and work OK. I'll give the 3rd one a shot.

Are you sure? yes | no

Dan Maloney wrote 06/02/2020 at 20:26

Interesting - my first thought on a fluid warmer was to wrap around the solution bag and warm that up in bulk. But your way makes more sense - just heat a small volume of fluid within the IV tubing before it gets infused. Makes so much sense. And extra points for using spent shell casings.

Are you sure? yes | no

Henrik Sorensen wrote 06/03/2020 at 04:55

Thanks :-) Heating time should be much shorter and thus making it quicker to deploy (I hope). Another thought was actually to make an even smaller one as a clip on much closer to the bag and as this meant for hanging near the solution bag. But, let's see. I expect to get some tubing today and having a prototype (straight milled piece of aluminium) made within the next couple of days, so I can check my concept.

Are you sure? yes | no

IV Heater

Description

Project Logs

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Pondering heat transfer....

Prototype heating block begun

Electronics prototype done

Brainstorming session...

Discussions

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