Day 7 Progress

The following 3 experiments were 'mock' robotic scenarios carried out over the past 7 days.  Our purpose was to investigate what causes the mold to change its growth patterns.  How can we control the movement of the mold?

First we conducted a Directional test.  The mold was placed at one end of a horizontal path of food.  It followed this path until it consumed the entire pile.  Instead of branching out towards the other pile of food near the top of the dish, it produced growth in all directions.  Even after finding the second pile of food, the mold continued to accumulate on the opposite side of the dish.  Towards the end of the week, the mold concentrated its growth in the direction of the second pile of food.  Perhaps the mold can be trained in this way.  However, it is undesirable that the mold branches out in all directions before concentrating growth in the preferred direction. 

Below are the results of the Repellent test.  Mold shows a strong aversion to the sleeping pills.  It seems that even pill residue inhibits growth.  When pills were moved from the right to left side near the mold, it grew the opposite direction and literally moved itself to the other side of the dish.  The pills are such strong repellents that the mold has not growth enough to interact with the sea salt that was placed in the center of the dish.  Pills are effective repellents but slightly undesirable because they severely restrict growth. 

A Scrape test was also conducted.  This petri dish previously held several piles of food and mold growth throughout the entire area.  All mold cells and pieces of food were scraped off the agar surface and deposited in a line at the bottom end of the dish.  Mold has since regrown and is now expanding upwards to fill the rest of the container.  However, several tiny bits of mold that were left on the surface have begun to grow in the upper area of the surface, interfering with the desired aesthetic.  Proper results can be obtained by designing a scraping device that is able to remove all mold from the surface.

Other findings:

After filling out the entire petri dish, mold will grow vertically.  However, since there is no agar solution on the sides of the dish, the mold grows in a different pattern.  In the absence of agar, mold cannot grow fine tendrils and instead clumps together in larger masses.  The patterns are just as beautiful.

Another investigation of vertical growth patterns.  A hole was dug out of the agar to remove a growth of common mold that had gotten into the dish.  The hole is in the mold's area of dense fractal growth, however, the growth in the hole seems to be even more dense.  Further study can be done by observing growth in a petri dish with 'hills and valleys' in the agar.

Results of the color test over the past 4 days:

...and a close-up showing the color gradient apparent in the main arteries.  New growth is yellow.

Amount of Food and Repellent Testing

We conducted two other experiments by varying the amount of food: one with little food and another with a greater amount.  The results show different responses to the different food amounts.  See below:.

DAY2

Small amount of food

Large amount of food

DAY4

Given a large amount of food, the mold takes longer to enter the branching mode because its immediate food source is abundant.

When given a small amount of food, the mold branches out quickly in search on the next food source. 

Based on previous results from the Repellent test dish, we wanted to know what would happen if we introduced a repellent to an already healthy growing environment.  Stay tuned to see what happens...

5 Day Progress

Progress Shots:

Mold seems to be following the trail of food, though it has now branched out to cover most of its container.  The arteries between food piles, following the trail, are the strongest.  The repellents are effective.  This container has the least growth of them all.  Mold has not grown out of the corner where it was originally placed.  It has not even grown near the sleeping pills, as we thought it would.  The coloring experiment is producing beautiful results.  However, the food coloring was absorbed by the agar solution as well as the mold.  It is difficult to see the coloring of the mold independent from the agar.  We will try another experiment that isolates the colored oats so they don't color the agar.

Now that we have observed the basic characteristics and growth speeds of the mold, we will begin to create mock-robotic petri dishes.  Stay tuned.

2.5 Day Progress (60 hours)

Mold is still growing at a reduced rate because of its abundant food supply.  We will soon be modifying the experiments to test growth rate when in search of food.  In the meantime, here are some updated pics:

The mold in the original petri dish has not been fed since it left the lab.  It is relentlessly trying to escape the dish and has succeeded in growing into the surrounding bubble wrap after multiple attempts to kill off extraneous growth.  This was a nice discovery, proving that the agar solution is not necessary to successfully produce growth.

Mold is successful at following a path of food.  We will soon divert that path and see if the mold follows.
Example 1:

Example 2:

Mold is growing away from known repellents.  However, growth in any direction is typical when searching for food.  We are going to let this one keep growing as is and see if it moves towards the sleeping pill once it fully populates its immediate area.

Color change is not working as well as we thought.  There is a slight red hue to the mold that is more apparent in the original mass of nuclei than in new growth.  We are going to move the blue colored oats closer to new growth to quickly see if any color mixing occurs.

Mold and I

Some progress photos of our experiments with slime mold:

These are the different variables we are testing:
Directionality of growth, reaction to food coloring, speed of growth when given a large or small amount of food, reaction to repellents like salt and sleeping pills, and ability to follow a path of food.

Experiment set up:

Some before and after shots of mold growth.  Photos were taken 12 hours apart.  Growth has since slowed because the mold reached its food source.  Once the mold has exhausted its immediate supply of food, it will branch out again in search of the next pile of oats.

Out of the Box

This is our slime mold, shipped to us from Carolina Biological Supply Co.  The large pieces are oat flakes which the mold is feeding off of.  We are currently in the process of constructing larger petri dishes to test the mold's behavior in different environments.  We have placed an LED in one area of this dish to quickly study the effect of light on the mold.  Results to come.

Slime Mold Facade Treatment

When restrained, the mold will travel along a predetermined path in search of food.  This activity can act as a facade treatment.  A slime mold facade would be able to constantly respond to changes in its environment by relocating food sources in response to a variety of factors.  Also, the mold is sensitive to light.  Strong light sources can repel the growth.

Slime Mold Networking

Slime mold grows in the form of an interconnected network as part of its normal strategy to explore new sources of food.    When it encounters numerous food sources separated in space, the slime mold cell surrounds the food and creates tunnels to distribute the nutrients.

To test how efficient the mold could be, Toshiyuki Nakagaki’s team duplicated the layout of the area around Tokyo: They placed the slime mold in the position of the city, and dispersed bits of oat around the “map” in the locations of 36 surrounding towns.  The mold explored slowly at first, but like any good transportation engineer it began to figure out traffic patterns.  Those carrying a high volume of nutrients gradually expand, while those that are little used slowly contract and eventually disappear.

The mold is able to replicate the existing subway network of Tokyo and connect important nodes by growing on a flat moist surface.  What could be of interest here is how the mold can navigate topography to reach certain nodes.  This could be a useful city planning strategy or means of locating service trails through national parks.  A digital mathematical model of this same process could be supplemental to GIS systems.

Another area of interest would be to investigate the limits of the mold in exploring its surroundings for new sources of food.  For example, how far will the furthest reaching cells travel in search of nutrients.  Can the mold travel vertically?  Can the mold be trained to search in specific directions by repeatedly placing then removing a food source?  What other processes can the mold simulate?

Inflatable sketches

Dry Ice Bubbles

Strong bubbles

http://www.google.com/m/url?client=ms-android-att-us&ei=DPOxTpjrLbTciQKa7AE≷=us&hl=en&q=http://www.youtube.com/watch?v%3DU7DbfNnxtps&source=android-browser-key&ved=0CBYQuAIwAQ&usg=AFQjCNG05uFkJSiLl6_dlJqCuoAKy6EN-w