Building A Better Baby Bottle Boiler

[Sebastian Foerster] hasn’t been at his blog in a while. He and his wife just had twins, so he’s been busy standing waiting for formula or milk to warm up. Being a technical kind of guy, he took a look at the tools currently on the market to do this, analyzed them, and decided instead to do it himself.

[Sebastian] looked to his Nespresso Aeroccino – a milk frother designed to give you hot or cold frothy milk for the top of whatever beverage you decide to put it on top of. It made the milk a bit too hot, 60°C, but once it got to the temperature, it would shut off, so if [Sebastian] could get it to shut off at a lower temperature, he had found the solution!

After taking the Aeroccino apart and going over the circuit, it seemed like a simple design relying on a resistor and NTC (negative temperature coefficient) thermistor connected to an ATTiny44 microcontroller. [Sebastian] didn’t want to have to reprogram the ATTiny, so he looked at the resistor and NTC. The resistor and thermistor create a voltage divider and that voltage is read in by the microcontroller through an analog pin. After looking up some info on the thermistor and replacing the resistor with a potentiometer, [Sebastian] could adjust the shut-off temperature while measuring with a thermometer. When he got the temperature he liked, he reads the value of the potentiometer and then replaces it with a couple of resistors in series.

Now [Sebastian] gets the babies’ bottles ready from fridge to temperature in about 25 seconds. He doesn’t have to worry about keeping an eye on the bottles as they heat up. We’re sure that getting two bottles ready in under a minute is much better on the nerves of new parents than waiting around for ten minutes. For more fun with thermistors, check out our article on resistors controlled by the environment or check out this bluetooth bbq thermometer!

34 thoughts on “Building A Better Baby Bottle Boiler

  1. Pro tip: from a father of many children who has lost count of the number of bottles he has made up.

    Use a microwave oven with the same container and amount of water and it will come out exactly the right temperature every time, once you have the process calibrated, then add the formula. So long as you don’t change any of the variables it is the fastest and most reliable method I have ever tried. It works because you are putting a fixed amount of energy into a fixed volume of water. Even then most parents let a drop of the milk fall onto their wrists to double check and then lick it off to ensure the milk tastes the same because if it is in any way different you really should think twice about giving it to the child. Interestingly the child will also reject milk that tastes different if for example you change brands.

    Whatever you do don’t use any steps in the process that introduce bubbles into the milk or your child will suffer for it, and feed them less but more often then they will never puke on your shoulder when you burp them.

    1. I completely agree. Don’t try and over analyze this problem. I’ve had two boys and over engineering this problem is easy. Just figure out a good time and lather, rinse, repeat to make sure the formula is good.

      It is easy to over engineer this problem but any seasoned dad knows exactly how long to put the formula in the microwave to make a midnight feeding last 10 minutes instead of 30.

    2. It was my understanding that microwaving baby bottles was a bad idea as it may heat unevenly, leading to hot spots and cold spots. I figured a good stir could solve this, but never bothered as I just ended up with a warmer from a shower.

      1. I never said anything about warming the actual made up bottles, that doesn’t make sense if you have to do more than 1 at a time anyway as you are duplicating effort.

        You heat the water, not the formula, the powder goes in after the water is warm enough as it will then dissolve a lot faster and not need to as much mixing effort which can introduce air bubbles that can become painful “gas” in the child’s stomach.

        So unevenness of temperature is not a problem, however you can test this.

        Add cold water with blue food dye to the bottom of a bottle then gently add hot water that is dyed red, finally invert the bottle and handle it as you would up to the point of giving it to the child, does the red-blue lamination rapidly and completely turn into an even purple? Yes it does. I know this as it is one of the STEM experiments the child will be doing later on when they are in primary school. :-)

    3. While it’s probably true that infants will develop rigid preferences if the taste of their milk is too stable, and that such rigidity could result in feeding problems, the compounds and taste of breast milk vary a lot with mom’s diet. So, there probably isn’t anything wrong or bad with variations in flavor (as long as the milk isn’t bad/spoiled), and it could even make feeding easier in the long-run by exposing the child to more flavors. There’s lots of research how exposure to flavors in childhood, infancy and even in utero (via the mom’s diet) have measurable effects on flavor preferences later in life.

    4. Do not microwave formula:

      “Never warm up formula in a microwave, as it may heat the feed unevenly and burn your baby’s mouth.”

      Do not microwave expressed breast milk:

      “Don’t use a microwave to heat up or defrost breast milk. This can cause hot spots, which can burn your baby’s mouth.”

      1. If you were to read the original comment, you would notice that it refers to heating the water and then adding formula afterwards. It is, as the OP says, by far the easiest process once you figure out how many seconds are required.

      2. 1. You heat the water not the formula, heating formula doesn’t make sense anyway.

        2. Hot-spots in reheated materials are easily manageable, with a knowledge of basic physics, see my other comment.

  2. I’m glad some people’s microwave is consistent our Panasonic is atrocious for consistency in heating babies bottles. The time required is too small get a consistent temp. We have 2 boys under 2, one will drink his milk at almost any temp and the other is as fussy as, if it’s not hot enough he just spits it out.

    I’ll have to dig out my old milk frother and give it a go…

    1. So just adding a large glass of water to balance the load was beyond your abilities? Excuse my snarky incredulity, but really? Are you claiming that it is a scale issue and there is a non-linearity at the bottom of the range? Just move up the range, all you need to do is be consistent with your variables.

    1. Drip coffee makers work by boiling water. The steam is required to push the water up into the basket. You don’t want to boil milk, as that changes its properties (and makes it taste unpleasant). Also, you wouldn’t want to run milk through it as it will be impossible to properly clean later.

      So if you plan to use the heating element from a coffee maker to just heat and not boil, you’ll have use it to boil water and then use the heat from that to warm the milk.

  3. I agree, making water hot to put the formula in it is well done by the microwave…
    But if you use pumped milk I am afraid of warm spots. In the frigde the milk splits a bit in “water” and “fat” parts. I wont kill the nurtients of the mother’s milk…

    1. Place bottle inside larger container with additional water which acts as a susceptor and evens out heating, just be very consistent with the volumes involved and keep everything centred.

    1. It does sometimes. You are fortunate if the mother can always be present and available to breastfeed the baby, and both the mother and baby are capable of breastfeeding. This is not always the case, and sometimes milk must be pumped, refrigerated (or frozen), and consumed later.

      A good engineer always considers corner cases.

      1. My mother worked until I were 6 years old. She could carry me sometimes, other times she “scaped” in the testing times to feed me. However, I realize that this is not possible in all the cases.

        In the vast majority of the cases both are capable of breastfeeding, but this is another thread.

        The not-a-hack was only the typical trolling joke, but this hack is great.

    2. Actually it is very complicated and the changes in the brain required to trigger lactation also influence the levels of other neurotransmitters and this can contribute to postnatal depression.

      However breast milk is the ideal option as there are other components in fresh human milk that formula can never replace fully.

      Most people have to settle for a combination of both to ensure sufficient weight gain in the child, however excess feeding is just as harmful in the long run as underfeeding. Like I said above, for most families it is not a simple as it seems.

      1. I’ve been fed by my mother until I was five years old or so. Obviously I started to eat omnivorously (tasting the food, not eating huge amounts) when I were a year old or a bit less. Then, gradually I started to demand less breastfeeding and more “food” until my own body decided that it was enough.

        The influence of the breastfeeding in postnatal depression is very controversial. I think that this won’t happen to the vast majority of the people.

        The mammals are “designed” to be breastfed. I did not had any problem with my weight. In fact, the problem with many formula-fed humans is that they are overfed (or better yet, they don’t control what they eat with the same precision as the breastfed ones). In fact, the weight tables used since 2006 are based on breastfed children (at least on the U. S.) Unluckily on my country these tables

        1. Oops, the comment lost part of the text

          Unluckily on my country these tables are yet in the popularization phase and some closed-mind pediatricians refuse to use them.

        2. Your anecdotal experiences are irrelevant, sorry but that is just not how science is done. They are not statistically meaningful.

          As for PND, that is not controversial at all, the hormonal and neurochemical changes and their associations are well documented, the differences between individuals are because, well individuals are individual, there are variations. However the key processes remain the same, dopamine levels must drop in order for prolactin levels to rise.

          Mammals are not designed, period, mammals evolved and humans stopped that sort of evolution the moment they started using their minds to change their environment to compensate for their maladaptations to the environment. i.e. more than 10,000 years ago, about 500 generations, or more, so that is a lot of unnatural selection.

          1. I know that the scientific method relies on other methods… unless doing qualitative analysis ????. My opinion did not pretend to be statistically meaningful, I’m simply too chatty. However, we have thousands of years without formula milk behind us (the only difference is that now we can save the non-breastfeedable creatures).

            Can you post references (DOI is ok) to any studies relating the breastfeeding with the reduction of the dopamine generation in the brain? I never heard of this. Are you sure that the postnatal depression is somehow related to the breastfeeding.

            I added quotes to avoid the literal interpretation of “designed” obviously we *evolved* but it seemed funny, as the original post was talking about engineering. Did we stop evolving? When and how? Are you really saying that we are evolving with “unnatural” selection since thousands of years ago? This can be discussed. We are animals and we evolve like it.

            The idea of changing our environment to overcome maladaptations deserves a full paragraph. Well, why the vast majority of the birds make a nest, the bees construct honeycombs or the rabbits dig holes? Is the turtle the one animal fully adapted to the environment?

            This is a truly interesting conversation.

          2. Do your own research, answer your own questions and you will learn more. That phrase I used, did you even run a google search on it? Don’t be, intellectually, lazy. Do you really think I would just make things up? And yes one change does lead to the other, in vulnerable people, as the systems involved are closely coupled, this is why when they are not operating optimally that they can have such side effects. I never said the phenomena was direct and ubiquitous, obviously different people are, biochemically different, otherwise we would all react to medications the same way, including antidepressants. This stuff is rather obvious, IF you try to think about it rather than just be a chatty questioner.

            You really need to learn more about these subjects your understanding is very shallow. Do you think that a bird knows how to build anything, or why it should, no the nest is a behavioural manifestation of natural selection, it is automatic not cultural, human knowledge is cultural.

  4. I did a similar project for my babie’s bed; a heater and cooler attached to a silent fan + particle filter, a temperature regulator, a timed humidifier and a closed crib also known as air crib. Perfect temperature every night, no sheets or pajamas, just diapers also I can gradually down regulate the temperature when it’s time to introduce sheets.

  5. Many comments have been written about how to feed infants or not…… But is this a site for young fathers?
    Use only one resistor to change the functioning of the device as it is necessary for you. This is really a very good hack! +1

  6. Many comments have been written about how to feed infants or not. But is this a site for young fathers?
    Use only one resistor to change the functioning of the device, as it is necessary for you. This is really a very good hack!

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