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Can we use material intelligence to power robots?

Can we tune a shading mechanism to its natural environment?

Can a wall become more dense as the weather changes?

Can we use magnetic and tensile forces to amplify hygroscopic forces?

Can we use math to see the city?

Can nature design and build for us?

Can a window network breathe?

Can a building skin behave like a sea creature?

All work my own unless otherwise credited.

Important Questions Raphael Kay | University of Toronto

Can we use material intelligence to power robots?

Raphael Kay and Kevin Nitiema, 2019. External guidance from Nicholas Hoban (UofT) and David Correa (Waterloo).

When a moisture-dependent material (wood) and a moisture-independent material (resin) are fabricated as a two-material bilayer, a change in moisture activates a material-wide bend.

Biological organisms like pinecones use material intelligence to drive movement. Their scales open and close elastically due to hygroscopic expansion differences in their cell layers. This allows repeatable motion without the use of active energy, a subject of particular interest as pressure grows to move away from energy-intensive and high-maintenance electromechanical systems.

Through a similar pinecone-like design, we present a hygroscopically activated robot, capable of one-dimensional locomotion. Its legs are comprised of a material bilayer of a moisture-reactive maple veneer and a moisture-non-reactive resin coating, inducing a bend with a change in local relative humidity.

Image: ICD

Rather than fabricating a material-wide bilayer, it is also possible to fabricate a localized bilayer. This allows controlled bending along a predetermined axis, almost like a hinge.

Depending on the location and thickness of the hinge, the bend degree can be calibrated to relative humidity.

As such, a bend in a bilayer can be programmed to activate at a certain relative humidity level, and with a certain degree.

Material bilayers can be calibrated to bend at a certain angle relative to their fastening seam. This is determined by the magnitude of the angle between the grain direction of the wood and the fastening seam. As this angle approaches 90 degrees, the bend effect becomes almost negligible.

Material bilayers can also be calibrated to bend with either an increase, or decrease, in humidity. If a bilayer is fabricated in a low moisture environment, it will bend in high moisture. Similarly, if a bilayer is fabricated in a high moisture environment, it will bend in low moisture. For example, the bilayer on the left in both of the above images was fabricated in a low moisture environment; where as the bilayer on the right in both images was fabricated in a high moisture environment.

The robot’s locomotion follows a four-step cycle. The first step involves depositing moisture to the front legs in an otherwise low moisture environment. The second step involves depositing moisture to the back legs in an otherwise low moisture environment. The third step involves removing moisture from the back legs in an otherwise low moisture environment. And the fourth step is passive, allowing the robot to return to its rest state.

Each cycle takes around half an hour to complete in low humidity. The above image illustrates four sequential cycles, with a total displacement of 43 cm in 127 minutes.

Can we tune a shading mechanism to its natural environment?

35% RH

Raphael Kay and Kevin Nitiema, 2019. External guidance from Nicholas Hoban (UofT) and David Correa (Waterloo).

35% RH

85% RH Almost all experimentation was carried out in an environmentally sealed humidity chamber.

Preliminary tests were carried out in order to test the calibration of the bilayer opening to relative humidity.

a 85% RH

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Wood is a hygroscopic material. When dry it absorbs moisture from the atmosphere, and when wet it returns moisture to the atmosphere. As a consequence, with a change in moisture content, wood shrinks and swells anisotropically. This means that when coupled with a non-hygroscopic material to form a bilayer, the ensuing expansion disagreement between its layers causes a bend in the overall bilayer. As such, when a hygroscopic/non-hygroscopic bilayer is fabricated, moisture can be seen as a form of passive energy to fuel an active kinetic process.

The presented window shading system can be calibrated to open and close with a certain degree of humidity. Moisture can either be passively introduced or removed as a function of the natural environment (right), or actively introduced and removed through a targeted mechanical system (above).

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25% RH

Can a wall become more dense as the weather changes?

Raphael Kay and Kevin Nitiema, 2019. External guidance from Nicholas Hoban (UofT) and David Correa (Waterloo).

25% RH

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a 85% RH

65% RH

b When a moisture-dependent material (wood) and a moisture-independent material (resin) are fabricated as a two-material bilayer, a change in moisture activates a material-wide bend. Long bilayer strips bend quickly as a function of moisture changes, and bend in on themselves. In a contained system – for example, trapped within window panes – this bending phenomenon causes a stacking effect that simulates the activation of a shading mechanism.

b 85% RH

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The density, so to speak, of a window shade can be calibrated to the relative humidity within the enclosed window system, as illustrated to the left. As this bend effect is elastic, the stacking effect is generally reversible.

65% RH

25% RH

65% RH

25% RH

65% RH

Using partitioning systems, it is also possible to control the form that a shading mechanism takes.

For example, certain window portions can be activated at different times for different optical and thermal purposes.

The images to the right illustrate the range of optical transmission for given relative humidity levels within the enclosed window shading mechanism.

85% RH

85% RH

25% RH

Can we use magnetic and tensile forces to amplify hygroscopic forces?

75% RH

25% RH

Raphael Kay and Kevin Nitiema, 2019. External guidance from Nicholas Hoban (UoftT) and David Correa (Waterloo).

25% RH

75% RH

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75% RH

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A bilayer material bend can be generated if the material properties of the respective layers differ. In this case, a hygroscopic (responsive to moisture) and non-hygroscopic (independent of moisture) layer are fastened to one another, inducing a bend. Compounding this bend effect, however, is an magnetic effect, as a series of magnets (opposite poles facing one another) are attached to each bilayer system.

As can be seen above, the difference in the displacement between the two hygroscopic bilayer systems is almost 50%. This (likely) represents the magnetic effect, compounding the hygroscopic bend between the two bilayers.

x c A similar amplification is presented above, however, instead of magnetic activation, the bilayer bend is being amplified with a tensile force. Two bilayer systems are fastened to one another using a string connection. As can be seen, this (likely) amplifies the hygroscopic bend effect by a third.

Can we use math to see the city?

Raphael Kay, 2018. External guidance from Marianne Hatzopoulou (UofT, Civil Engineering, all data) and Ethan Heimlich (UofT, Statistics and Mathematics).

From geospatial air pollution data, I completed nine studies visualizing air pollution against factors such as altitude, building height, and proximity to a major road. From these nine studies I mathematically transformed three-dimensional geospatial data into two dimensions, such that we could compare the quantitative conclusions of these data studies.

PLOTTED STUDY DATA Scaled Pollution Concentration (PPB) 140

STEP 2: Use matrix to linearly transform surface into 2D plane 30 1C Private Vehicle Traffic

n1 n2 n3 n4 n5 n6

Line of Best Fit

X Y Z

2C Public Vehicle Traffic

1A Air Pollution Site Concentration 00 m

STEP 1: Generate 3D surface to represent each study 1A Air Pollu�on Site Concentra�on 00 m

2A Air Pollution Site Concentration 90 m Line of Best Fit

STEP 3: Compare post-transformation representations w/ lines of best fit TOTAL DRAWING SET Line of Best Fit

2A Air Pollu�on Site Concentra�on 90 m

1C Private Vehicle Traffic

3A + 3B Survey Response Discrepancy

2C Public Vehicle Traffic 2B Building Height

Line of Best Fit 2B Building Height

3A + 3B Survey Response Discrepancy

Can nature design and build for us?

Raphael Kay, Kevin Nitiema, Charlie Katrycz, 2019. External guidance from Benjamin Hatton (UofT, Materials Engineering).

Nature self-designs and self-forms. Embedded in its processes is both the information necessary for conception and the physical capacity for construction. Architects and engineers have long taken advantage of nature’s capability to self-design. However, they have rarely taken advantage of nature’s capacity to self-form. Most often natural inspirations are modelled using data-intensive algorithms, and fabricated using cost- and energy-intensive machinery. In an architectural context, nature is rarely utilized to self-fabricate for free. Accordingly, we propose an adaptive architectural skin that is not only self-designed, but self-formed: a millifluidic vasculature constructed using a pressure instability between fluids. This research will represent one of the first manifestations of self-formation at an architectural scale, and will serve as an adaptive vasculature to regulate both internal temperature and light intensity in an applied setting.

The above image explains the fluid tunnelling process that occurs as a result of the Saffman-Taylor instability.

This instability occurs when a less viscous fluid (in the above case air) displaces a more viscous fluid (in the above case soap) in porous media.The instability produces a branched fractal pattern similar to the structure of mammalian tissue vascularity (Zamir 2001), and its design (fractal bifurcation) follows that of an optimal flow pathway for microfluidic networks (Bejan 2001; Chen et al. 2010; Wu et al. 2010).

The above sequence of images illustrates the introduction of a less viscous fluid evenly on both sides of a more viscous fluid, resulting in an even fluid displacement, and an even fractal bifurcation structure.

Image: Roger Beaty

The fractal bifurcation pattern produced from the above fluid tunnelling process represents the optimal flow pathway with the maximum flow efficiency for fluidic transport. This network accordingly follows Murray’s Law, stating that when a network branch splits (with radius r), the thickness of the resulting new branches (with radius r1 and r2) is optimized for flow efficiency (Wu et al. 2010). In its simplest form, Murray’s Law states: r3 = r13 + r23 Murray’s Law is obeyed in both the vascular and respiratory systems of animals and in the xylem in plants. It is also obeyed in river branching, as displayed above. Accordingly, the resulting fluidic network produced using the Saffman-Taylor instability is also optimal for delivering or removing heat within a fluidic network (Bejan 2001; Chen et al. 2010).

The above sequence of images illustrates the introduction of air inside a pocket of silicon. The resulting channel network can be cured into a soft polymer permanently, and can be utilized within a microfluidic window unit. This above experiment was carried out by a colleague, Charlie Katrycz.

Image, experiment: Charlie Katrycz

Can a window network breathe?

Raphael Kay, Kevin Nitiema, Charlie Katrycz, 2019. External guidance from Benjamin Hatton (UofT, Materials Engineering).

We have explored fluid displacement via pressure instability as a means of channel network fabrication (see above project). Beyond this, however, fluid displacement has further potential in channel network operation.

Here, we examine the possibility of a pneumatically actuated expanding and contracting fluidic channel network, operating as a lung. By actively varying the pressure with which a non-viscous fluid (air) is introduced in a viscous fluid, a fluidic network self-forms and self-dissolves, allowing for adaptive thermal and optical capability. More specifically, through pneumatic actuation, we can control the nature (size, geometry) and very existence of a channel network embedded in a window membrane with fluid transportation capability.

Not only is this process completely reversible, the proposed channel network can more importantly reform uniquely - with varying channel complexity, channel thickness, and network size - depending on the pneumatic input, as a function of the thermal and optical requirements for fluid flow. Iterations of a self forming channel structure are displayed above.

The image below displays a fluid pocket self formed through fluid displacement from multiple injection points.

This image serves to show the potential in drastically altering the geometric nature of a self forming and self dissolving fluidic network by controlling the location and number of pneumatic actuation points, along with the fluid pressure at each point.

Image, experiment: Charlie Katrycz

Ultimately, if fluid displacement can be controlled, so too can the transmission of heat and light through the self-forming and self-dissolving fluid pockets. The above image illustrates the potential for the switching of fluids at different temperatures, and with different IR reflectivity. These experiments were carried out by a colleague, Charlie Katrycz.

Image, experiment: Charlie Katrycz

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The above image shows the reversible self-formation and self-dissipation of a fluid pocket within a more viscous fluid, all embedded within a rigid window frame.

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The figure to the left shows the temperature and light intensity change with the formation of a fluid pocket over a 10 minute long period. The initial temperature was recorded once stable (20 minutes), and the final temperature was recorded once stable (3 minutes). The above images show the time-steps in the creation (left) and dissipation (right) of a fluid pocket.

Can a building skin behave like a sea creature?

Raphael Kay, Kevin Nitiema, Charlie Katrycz, 2019. External guidance from Benjamin Hatton (UofT, Materials Engineering).

Bottom Image: Lutz Auerswald

The above figure compares the expansion of a pressure-generated fluid pocket formation (top) to the expansion of chromatophores beneath the skin of krill (bottom).

Several sea creatures like squid, krill, and brittlestars perform adaptive shading through the control of pigment-filled cells underneath their skin. Buildings, on the other hand, perform adaptive shading through electro-mechanically driven components that are often costly, energy-intensive, and high-maintenance, prone to failure over time. As buildings account for about half of the carbon footprint of the United States, the design of climate-adaptive and energy-efficient building skins is vital. Accordingly, we developed a bio-inspired architectural skin, modeled after pigment-cell activation within sea creatures, in which fluid pockets self-emerge and self-dissipate, activated locally to regulate heat and light transmission into buildings.

Image: Aya Masagaki and Ryozo Fujii

The above figure illustrates the reversibility of the chromatophore activation patterning over time for an adaptive shading effect in pencilfish.

The above figure shows preliminary experimentation on the nature of self-formation via fluid tunneling between air and molasses - and the nature of light transmission. The right image shows the growth of hormone-activated chromatophores on the skin of fish over time.

Image: Richard Wheeler

The figures above and to the right show the successful automation of the formation and dissipated of a fluid pocket, in this case by motion input. In the future, we hope that a biological photo-organism will act as an input sensor, as is the case in nature. If photo-organism solutions are used, our very bio-material could act as its own sensor and actuation driver, telling the system when to displace itself. We have accordingly begun to study photo-bacteria grown in thick gels, as many algae species cannot survive in viscous solutions.