Levitation based inertial sensing

Key takeaways

Levitation based inertial sensing belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Levitation based inertial sensing to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Levitation based inertial sensing from memory before moving on to harder problems.

Reference excerpt

Levitation based inertial sensing is a new and rapidly growing technique for measuring linear acceleration, rotation and orientation of a body. Based on this technique, inertial sensors such as accelerometers and gyroscopes, enables ultra-sensitive inertial sensing. For example, the world's best accelerometer used in the LISA Pathfinder in-flight experiment is based on a levitation system which reaches a sensitivity of < 10 − 15 g / H z {\displaystyle <10^{-15}\,{\rm {g}}/{\sqrt {\rm {Hz}}}} and noise of < 10 − 14 m / s 2 / H z {\displaystyle <10^{-14}\,{\rm {m/s^{2}/{\sqrt {Hz}}}}} .

History The pioneering work related to the microparticle levitation was performed by Artur Ashkin in 1970. He demonstrated optical trapping of dielectric microspheres for the first time, forming an optical levitation system, by using a focused laser beam in air and liquid. This new technology was later named "optical tweezer" and applied in biochemistry and biophysics. Later, significant scientific progress on optically levitated systems was made, for example the cooling of the center of mass motion of a micro- or nanoparticle in the millikelvin regime. Very recently a research group published a paper showing motional quantum ground state cooling of a levitated nanoparticle. In addition, levitation based on electrostatic and magnetic approaches have also been proposed and realized. Levitation systems have shown high force sensitivities in the z N / H z {\displaystyle {\rm {zN/{\sqrt {Hz}}}}} range. For example, an optically levitated dielectric particle has been shown to exhibit force sensitivities beyond ~ 2 × 10 − 20 N / H z {\displaystyle 2\times 10^{-20}\,{\rm {N/{\sqrt {Hz}}}}} . Thus, levitation systems show promise for ultra-sensitive force sensing, such as detection of short-range interactions. By levitating micro- or mesoparticles with a relatively large mass, this system can be employed as a high-performance inertial sensor, demonstrating nano-g sensitivity.

Method One possible working principle behind a levitation based inertial sensing system is the following. By levitating a micro-object in vacuum and after a cool-down process, the center of mass motion of the micro-object can be controlled and coupled to the kinematic states of the system. Once the system's kinematic state changes (in other words, the system undergoes linear or rotational acceleration), the center of mass motion of the levitated micro-object is affected and yields a signal. This signal is related to the changes of the system's kinematic states and can be read out. Regarding levitation techniques, there are generally three different approaches: optical, electrostatic and magnetic.

Applications The sub-attonewton force sensitivity of levitation based system could show promise for applications in many different fields, such as Casimir force sensing, gravitational wave detection and inertial sensing. For inertial sensing, levitation based system could be used to make high-performance accelerometers and gyroscopes employed in inertial measurement units (IMUs) and inertial navigation systems (INSs). These are used in such applications as drone navigation in tunnels and mines, guidance of unmanned aerial vehicles (UAVs), or stabilization of micro-satellites. Levitation based Inertial sensors that have sufficient sensitivity and low noise ( < 10 − 9 m / s 2 / H z {\displaystyle <10^{-9}\,{\rm {m/s^{2}/{\sqrt {Hz}}}}} ) for measurements in the seismic band ( 0.1 m H z {\displaystyle {\rm {0.1\,mHz}}} to 10 H z {\displaystyle {\rm {10\,Hz}}} ) can be used in the field of seismometry, in which current inertial sensors cannot meet the requirements. There are already some commercial products on the market. One example is the iOSG Superconducting gravity sensor Archived 2019-03-02 at the Wayback Machine, which is based on magnetic levitation and shows a noise of < 1 ( n m / s 2 ) 2 H z {\displaystyle <1\,{\rm {(nm/s^{2})^{2}Hz}}} .

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Levitation based inertial sensing

Start with the simplest possible case. Write down what Levitation based inertial sensing claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Levitation based inertial sensing before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Levitation based inertial sensing ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Levitation based inertial sensing

In research: Levitation based inertial sensing appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Levitation based inertial sensing in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Levitation based inertial sensing is common in secondary-school and first-year university syllabi. It links to neighbouring topics Levitation, Sensors, so understanding it makes those chapters shorter.
In everyday life: Look for Levitation based inertial sensing outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Levitation based inertial sensing in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Levitation based inertial sensing means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Levitation based inertial sensing out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Levitation based inertial sensing in simple terms?

Levitation based inertial sensing is a new and rapidly growing technique for measuring linear acceleration, rotation and orientation of a body. Based on this technique, inertial sensors such as accelerometers and gyroscopes, enables ultra-sensitive inertial sensing.

Why does Levitation based inertial sensing matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Levitation based inertial sensing?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Levitation based inertial sensing.