Sensors Scatter to the Winds

In recent years, a technological revolution has brought about a new era of data collection and monitoring through the development of tiny, low-cost sensors and processing units. These miniature devices have opened up a world of possibilities for applications ranging from environmental monitoring to the optimization of agricultural operations. What was once a limitation of our ability to gather data has now shifted to the challenge of efficiently distributing these devices across the vast areas to be monitored.

Advancements in microelectronics have made it possible to create sensors that are not only tiny but also affordable, allowing for large-scale deployment on a budget. These sensors can measure a wide range of parameters, from temperature and humidity to air quality and soil moisture, providing valuable insights into the state of our environment and agricultural landscapes.

But the true potential of these sensors lies in their ability to be scattered far and wide, creating sensor networks that offer real-time data collection and analysis. Environmental monitoring, for instance, benefits from sensor networks deployed in remote forests, urban areas, or bodies of water, providing scientists and policymakers with a wealth of data to make informed decisions about conservation and resource management. In agriculture, sensors placed throughout fields can monitor soil conditions, crop health, and weather patterns, enabling precision agriculture techniques that optimize resource usage and increase yields.

Inspired by the falling of leaves, researchers at the University of Washington have created a new type of battery-free robot that can change its shape to alter how it travels through the air. The trick is to make sure the sensors are evenly and widely dispersed — they would not do much good if they all fell into one big pile, of course. So that shape-shifting feature, which moves the robot from a chaotic tumble into a stable descent, can be triggered at different times among the robots in the swarm, which has the effect of distributing them over a large area. Critically, this mechanism requires very little power.

The paper-thin, 414 milligram microfliers are designed to be dropped from drones, after which they control their descent pattern to spread themselves out. Each robot is equipped with a Bluetooth-capable microcontroller, timer, pressure sensor (for altitude estimation), and a solar panel to harvest energy. The substrate has a Miura-ori origami fold that puts it into a bistable configuration. It starts in a flat position that allows it to chaotically drift long distances. But with a quick jolt from a solar-powered electromagnetic actuator, the flier snaps into a new configuration that lends itself to a stable descent pattern.

Each robot can be preprogrammed to change its configuration after a predetermined amount of time, or at a specific altitude. Or alternatively, the signal can be sent wirelessly via Bluetooth — although the range of this option is limited to about 200 feet. Due to their light weight and aerodynamic properties, the microfliers can travel as far as the length of a football field when dropped from an altitude of 130 feet under conditions of light wind.

The devices can be loaded with other types of sensors to meet the needs of a variety of applications, allowing them to capture data both in the air, and after they land. And with the help of the solar panels, they could potentially continue to collect data for long periods of time.

At present, the robots must be manually put into the flat configuration, then can only shift into the stable descent configuration once. The team is currently working to allow the fliers to switch back and forth between configurations at will. That could allow them to make more precise landings, even under conditions of turbulent wind.