Insect Chilling Chamber

by Johan J Ingles-Le Nobel
Last updated August 31, 2017

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Killing insects is by far the most common method used by extreme macro studio stackers to get their specimen ready, but there's got to be a better way that doesn't involve killing.

I don't like killing insects so this is a project that's ready on paper and awaiting the right time for me to build it.

The Big Plan

Peltier cooler

A Peltier, a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current.

These can be purchased directly from suppliers in the Far East and I have bought 3, but I am still not entirely convinced that this will achieve the desired result. Stay tuned...

The insect chilling chamber that I have designed on paper requires various skills to make, none of which I yet have, which is why it is taking so long. But the theory, I think, should be fine. Part of the problem here is that I cannot find any similar device anywhere, so there isn't really anything to base the design off other than trial and error on my part.

We know for a fact that insects will remain still in cold temperatures of 0ºC-5ºC , so in theory a chamber with a low temperature should create those conditions and enable a photographer to take an extreme macro stack of images. Sound easy but there are all sorts of engineering obstacles to overcome.

Observations

A cooled chamber is easy to source but building one for extreme macro requires special modifications. To allow for diffusion, I am using a 5 sides perspex shop display case, with a separate sheet for the bottom to be able to actually put the insect inside.

An opening will need to be cut in the side with some flexible thermal material that extends round the lens, so that I can put the lens inside without having to shoot through perspex, yet also keep the temperature cool. I suspect that I'll need to make this modular in some way to account for different lens and objective sizes.

I can monitor the temperature at various points inside the chamber with temperature sensors, and a nice to have would be the ability to set a target temperature then to have the thing beep when the sensors have reached the target temperature.

Arduino

Arduino microprocessor, the base for the device.

Arduino is an open-source electronic prototyping and programming platform allowing the creation of electronically programmed and controlled devices.

Lenses inside chilled chambers may lead to a possible condensation problem on the glass face, so allowance has been made for a small PC fan to blow the air across the face of the lens. Small, because a fan might lead to vibrations, which we want to avoid.

If there are too many vibrations then I may go back to a previous idea, which would be to use an aquarium air pump blowing air through a desiccant to remove and absorb the temperature released moisture.

With an insect inside a chilled chamber and a lens in a relatively inflexible position except for the Z-plane, some means needs to be available to move the insect in its own XYZ planes to make a nice angle to shoot the insect at. Various interesting materials like 3D printing or shapelock can be used to create the arms for a lightweight universal stage, ideally I'd like those arms to be controlled from outside the chamber, which requires motors controlled through Arduino. Stepper motors might seem to be an ideal solution but they require a current to keep them stationary. I have purchased various steppers and DC motors to test, but finding the worm drive mechanism to translate the motor rotation into efficient arm rotation (in which the motor doesn't bear the weight but the arms do) has been trickier. But I believe that I have found some, but small 4mm worm screws are expensive.

Electronic means need to be used to control the various parts of the device; the Arduino microprocessor platform looks to be ideal as it is relatively affordable and the programming is well documented. Arduino is already used to make all sorts of creations including stackshot-like stacking controllers.

The mechanism used to cool down a chamber must be out of the way and relatively easy to control. For the time being I have settled on some Peltier coolers which are relatively straightforward to program using Arduino although the power requirements are high. Although I was initially looking at using 3 Peltiers or even a peltier sandwich with fans inside to distribute the cooling effect through some large old Dell server heatsinks, I'm not entirely convinced that this is the best way to do the cooling as the convection effect of a very cool object may suffice.

Peltier cooling operates on a sandwich principle with -20ºC on the cool side and +40ºC on the hot side. To operate, Peltiers require a heat sink mechanism to absorb the heat on the hot side otherwise they burn out within seconds. I have purchased a Corsair Hydro water-cooling mechanism for a PC to do this for me, which is all also controllable through Arduino (ie the speed of the fans, speed of the pump). Copper is a good temperature transfer medium so I have some sheets of copper, which will be stuck onto the hot side of the Peltiers using silver oxide semiconducter glue with efficient temperature transfer properties.

It may prove neccessary to add other means to dissuade the insect from moving away from the spot that I need it to be to take the photo. For example, Insect-a-slip prevents arthropods from climbing out of traps, cages, or other containers and forms a slick barrier that prevents arthropods from obtaining a foothold on the treated area. It maybe useful to make an Insect-a-slip barrier.

Also, at the same time, a sugar coating on the target area might give a positive inducement for the insect to stay put. Or a jet of warmth, to make the 'stay here' area more attractive than other parts of the stems.

CO² can also be pumped into the chamber through an Arduino air flow sensor. CO² in high concentrations is an agent that reduces insect movement although insects assume somewhat unnatural poses if exposed to high levels. CO² can be purchased relatively cheaply through aquarium suppliers, it is sold precanned for underwater plant promotion.

Progress Report

At the time of writing, I have completed two Arduino courses, built 15 gadgets using Arduino, and sourced the base materials to be able to start construction. I'll resume working on this as the one of the next projects on the list, scheduled for Q4 2014.

Comments (10)

Article: Chilling Chamber
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Bolkey says...

Most useful would be a kind of narcotic that makes insects apathic rather than dead - death always seems to make for unnatural postures and twisted claws. Once I have used alcohol in too low a dose to kill a ladybird, only making it drunk as a fiddler. Luckily at sat down for long enough to shoot my stack. At another occasion, I used an even unintoxicated damsel fly, its wings hold firmly between pinchers. It would grab onto any straw I offerd. Somehow my pictures show more liveliness and more naturality than the ones made with dead insects.

Admin:
Couldn't agree more - I've heard of Hydrogen gas being uased to this effect but it also results on unnatural positions.
23rd June 2016 9:40am
Bolkey says...
I have been on this path: cooloing a tiny plastic fish tank by two largish peltier coolers. However, the coolers were inefficient to the extent of actually heating the fish tank. The heat found its way around the coolers back down. I stopped there, thinking that a frozen cooling pad of an ice-bag or a tabletop freezer (that, BTW, you shouldn't by from ebay but pick up at your local junk yard!) would do a better job. But I never worked out these ideas for I switched from insects to plants. 2bc...
23rd June 2016 9:40am
Peter Monbs says...
Have you thought about using carbon dioxide instead? First anaesthetise in pure CO2 - don't keep insect in it too long after it stops moving or it will "drown". Then just let CO2 fall from the end of a tube held a few cm above the subject to keep it under. I am a scientist and used to work on insects. This was my preferred anaesthetic. In my experience, if you get it right, the subjects recover with no ill effects. You can read more about this via PubMed. Carbon dioxide can be had in small cylinders from bicycle shops. It is used for inflating bicycle tyres in an emergency. It would seem fairly easy to adapt the inflators to the purpose of anaesthetising insects.
28th July 2014 9:35pm
Johan says...
Hello Peter - I was planning to add CO² as well via an Arduino controlled air flow sensor but I hadn't considered using it just on its own! Definitely food for thought, thank you
29th July 2014 11:27am
Charles says...
We had some success with this idea but we used a Coolermaster V8 CPU cooler and stuck a small plastic tray to the cold side of the peltier with heat sink paste. To get the fly into the tray we stunned it first with CO2 (from a fire extinguisher). The fly was illuminated with an led torch so the exposures were very long (1/4 sec), here is a stack of 17 shots - it stayed remarkably still over the whole sequence:
http://www.hughtomkins.com/59176/1060188/photography/world-of-the-flies

(The peltier was powered by some AA batteries).

7th June 2014 8:04pm
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