Insect Chilling Chamber

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

FacebookGoogle+Mail

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 (9)

Article: Chilling Chamber
[first] < 1 2
Grahame says...
Have been thinking How about a bar fridge.Take the door off and replace it with a thermal drop of some sort with hole for camera Temperature can be adjusted to within .1 degree at 5 degrees anything below down to zero is not easy because water plays all sorts of tricks .You would hsve to turn cooling off when taking photo because of vibration.(Know a guy that does temp control for hospitals)
just some thoughts
Grahame
20th December 2013 9:15am
Johan says...
I considered this initially, just buying an old fridge from eBay and ripping the door out. The thing is I need room for a microscope stage, diffusion, 3 flashes and the field monitor behind, so all this didn't seem like a very practical solution. The one I have now seems the most flexible on paper though actually making it is a different matter. But must get back to this - if for no other reason than snowflake macro seems very popular at the moment and Peltiers are an easy way to make some artificial snowflakes as well :)
20th December 2013 10:40am
Philhad says...
Hi - would love to do stacks of live insects as killing them i have never done yet. so good luck with the chilling chamber. your website extreme macro is brilliant and i have been into close up and macro for a while but having purchased the mpe65 to do some extreme macro i can see i have a lot to learn but you have made it a lot easier thanks
regards

Phil.

19th November 2013 11:53am
Johan says...
You've got an excellent piece of kit there, the Mpe is something I'd love to have. Best of luck with it :)
19th November 2013 12:54pm
[first] < 1 2
Page 2 of 2