Osmotic Microfluidic Device Inspired by Trees and Plants

Innovation: Academia

MIT

2017

Image: Alaric Sim / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Capture, Absorb, or Filter Liquids

The most common liquid used by living systems is water, which they require to survive. But there are many other liquids that provide nourishment, play a role in defense mechanisms, or serve other purposes. Water varies in its availability; it is sometimes plentiful and sometimes very scarce or only available as fog or mist. To minimize the energy required to capture, absorb, or filter liquids, living systems have strategies that take advantage of the unique properties of the given liquid. For example, water moves from a gaseous to liquid state when it encounters a surface colder than the air. Plants in forests that experience fog and clouds more than rain have strategies that condense liquid water from moist air.

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Distribute Liquids

Liquids include water, as well as body fluids such as blood, gastric juices, nutrient-laden liquids, and more. To survive, many living systems must move such liquids within themselves or between locations. Because of their properties, liquids tend to disperse unless they are confined in some way. To address this, living systems have strategies to confine fluids for transport, and to overcome barriers such as gravity, friction, and other forces. Some of these same barriers also provide opportunities. Trees and giraffes face the same challenge: how to move fluids (water and blood, respectively) upward against gravity. But their strategies are quite different. The tree moves water using capillary action and evaporation, possibly due to water’s properties of polarity and adhesion. The giraffe’s tight skin provides pressure to assist in blood circulation. and keep blood from pooling in the legs.

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Microfluidic device from MIT uses slow, steady osmosis and a sugar cube to continuously pump liquid.

Benefits

Reduced energy usage
Long lasting
Reliable

Applications

Electronics
HVAC Systems
Robotics

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure
Goal 12: Responsible Production & Consumption

The Challenge

Many robots require tiny, movable parts and pumps to power complex movements. These tiny parts are difficult and expensive to manufacture, they break easily, and they require external energy to operate.

Innovation Details

The microfluidic device operates passively, requiring no moving parts or pumps. It is made of two plastic slides with small, drilled channels. To create a sugar gradient, some of the channels are filled with both water and sugar, and others are filled with just water. A sugar cube is placed on the system to diffuse into the liquid. The device is able to to passively pump water from a tank to a beaker at a constant flow rate for several days, outperforming other designs that only lasted a few minutes.

Biomimicry Story

Plants contain a tissue called xylem that consists of many small transport tubes. These tubes conduct water and nutrients from the roots to the leaves.

See Related Content

a tree with white bark has roots growing over bright green grass

Biological Strategy

Roots Maximize Water Uptake

Plants

Roots of plants maximize water uptake by adapting their orientation to the environment.

a small bush of thick light green stalks with small red and green flowers stand in the desert with large dark green curving leaves around their base

Biological Strategy

Leaves and Root Maximize Water Collection

Desert rhubarb

The leaves and root of the desert rhubarb maximize water collection by directing rainwater to the plant's base and absorbing water from saturated ground.

References

Journal article

Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip

Nature Plants

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