It’s raining microchips. One day, they could float gently through the air while gathering environmental data, land on the ground and then disappear when their work is done. That’s the future a team of engineers see for what they’re calling “microflier”, a tiny winged microchip with designs inspired by nature.

The accomplishment belongs to a team of scientists at the Northwestern University in Illinois, who developed the microflier, a flying microchip that spins like a helicopter. It is the size of a grain of sand but with small wings and an aerodynamic design that allows it to fall in a controlled manner thanks to its barely visible propellers. The engineers used nature’s “manual” to get their inspiration for the microflier, analyzing the behavior of various types of wind-spread seeds.

How does that work? Instead of using a motor or engine, the tiny flying microchip uses the power of the wind to catch a flight, spinning through the ground at low speed. It is a stable flight, and the microflier can stay in the air for a long time, which is why it could prove to be useful for a variety of applications.

While nature has designed seeds with very sophisticated aerodynamics, the Northwestern team claims its microflier is better, as it is even smaller and its structure allows it to fall with more stable paths and at slower speeds than equivalent seeds from plants or trees.

The engineers built the flying structure to be used for purposes such as population monitoring, pollution monitoring, disease tracking and so on. And while this might look like a simple, limited device right now, researchers see its potential for becoming a highly functional electronic device. The microflier can be equipped with really sophisticated technology, such as tiny sensors, antennas for wireless communication, or embedded memory for data storage.

Norway' s capital Oslo will become the first city in the world to use wireless (无线的) charging systems for electric taxis, hoping to make recharging quick.

The project will use induction(电磁感应)technology, with charging plates (板) in the ground at taxi stands where taxis line up to wait for passengers,Finnish company Fortum, said on Thursday.

"Receivers will be in a taxi, and when it drives up to the charger, a wireless charging process will automatically start. This will allow the taxis to charge in a place where they would anyway be waiting for new customers, says Annika Hoffner, head of Fortum.From 2023 all taxis in Oslo will have to be zero emission (排放) and Norway wants all new cars to be zero emission by 2025. Among other nations, Britain and France have similar goals for 2040.

Fortum is working with US firm Momentum Dynamics and the city of Oslo on the system. It said the greatest difficulty with electrification of taxis is that it takes too much time for drivers to find a charger, and then wait for the car to charge.

"Time equals money when taxi drivers are working," said OleGudbrann Hempel, head of

Norway has the world' s highest rate of electric car ownership, partly thanks to measures such as free or discounted road fees, parking and charging points. If you buy an electric car, you do not need to pay the same taxes (税) as those on traditional cars,which are very high in the country.                                                                                                                

Last year, almost one in three new cars sold was electric.With just five million people, Norway bought 46, 143 new electric cars in 2018, making it the biggest market in Europe. It is ahead of Germany which bought 36,216 and France which bought 31,095,according to the European Automobile Manufacturers' Association.

It all began with an experience one of us (Arinzeh) had more than two decades ago. In 1991, a summer research experience at the University of California at Berkeley demonstrated how engineering could improve the lives of patients. Instead of working in a more traditional area such as automobile design, Arinzeh spent the summer after her junior year of college working in a rehabilitation laboratory.

Engineers there were designing new prosthetic (修复的) devices for patients who had lost limbs, and new assistive devices to help paralyzed patients move. The engineers would then collaborate with clinicians at a rehabilitation center to test their developments. Before that summer she hadn’t connected traditional engineering principles with the opportunity to solve biomedical problems. But by the end of those short months, Arinzeh was hooked on the promise of using mechanical engineering to help people move better.

Tissue engineering, a budding field at that time, offered a chance to move beyond building prosthetics. Damage to musculoskeletal tissues, such as bone and cartilage, and nervous tissue, such as the spinal cord, can be debilitating and can severely limit a person’s quality of life. In addition, such tissues cannot fully regenerate after a severe injury or in response to disease. Tissue engineers aim to fully repair and regenerate that tissue so that it regains complete function, but at that time researchers still had a lot to learn about cells and their support structures to solve these problems.

The earliest successes were with skin, in which researchers used dermal cells to generate grafts, leading to the first commercial products in the late 1990s. Researchers imitate nature, using cells as building blocks and developing strategies to guide the cells to form the appropriate tissue. Because stem cells (干细胞) are precursor (前身) to almost all tissue types, such cells are a promising source of these critical building blocks. But cells don’t grow and differentiate on their own. The cell’s microenvironment can influence stem-cell function in critical ways. Engineered microenvironments, or scaffolds, can effectively promote stem cells and other cell types to form tissues. To construct such scaffolds, some important tools are what are called functional biomaterials. These materials respond to environmental changes such as PH, enzymatic activity, or mechanical load, and their composition can mimic or replicate components of native tissue.

One of us (Arinzeh) wanted to use functional biomaterials to create three-dimensional tissue-like structures where cells can grow, proliferate (增殖), and differentiate, ultimately forming and regenerating tissue. Our group’s work started with bone studies in the 1990s, eventually moving into cartilage and the spinal cord over the past decade. The overall goal is to produce structures that could someday help patients struggling with severe injuries and movement disorders to move freely. For bone repair, our group has studied composite scaffolds consisting of polymers and ceramics that provide both mechanical and chemical cues to repair bone. Piezoelectric materials, which respond to mechanical stimuli by generating electrical activity, are used to encourage the growth of nerve tissue as well as cartilage and bone. Glycosaminoglycans (GACs), a major component of native cartilage tissue, provide growth factors to promote tissue formation, and Arinzeh has designed biomimetic scaffolds that incorporate these molecules. After all these years, the promise that seemed so enticing in 1991 is becoming a practical reality, with huge implications for human health.