RFID technology is a revolutionary step in the field of asset identification & tracking. In a business/supply chain environment, identifying the large volume of individual products, become a difficult task. In addition to that, with the rising volume, the chances of errors also increase. Products like wet inlay or dry inlay, are extremely popular RFID solutions for such issues.
So, let’s discuss the differences between wet inlay and dry inlay in detail.
What is RFID?
It refers to Radio Frequency Identification, a wireless data communication technology that relies on the use of radio signals. It is a type of Automatic Identification & Data Collection (AIDC) system, that uses radio waves to identify assets and provide tracking capabilities. So, let’s take a deeper dive into RFID technology.
What are RFID Inlays?
A typical RFID system consists of a tag, reader, and antenna. The tag is generally small in size and made of plastics like ABS. An inlay simply refers to the functioning part of the tag. It consists of a small antenna connected to a chip that stores information, which is then attached to a substrate layer. Every tag contains an inlay inside of it, that it requires to function. But some systems just use an inlay without any outer layer of protection.
Types of RFID Inlays
As we’ve discussed above what an inlay means, we can further classify inlays into two classes, namely – Wet & Dry. A Wet Inlay consists of an antenna & chip sandwiched between a substrate layer and an adhesive layer on either side. These types of inlays are self-adhesive and do not require any additional help to mount on the surface of items.
A Dry Inlay is pretty much similar to the wet ones, with one exception. They do not have a self-adhesive layer on them, thus, requiring external help to be able to mount items. Dry tags are generally put inside cotton/polyester labels, or attached to items with the help of self-adhesive tapes.
Now that you know the basic difference between wet & dry inlays, let’s check out how they work.
Dry vs Wet RFID Inlays: Application & Comparison
Although they may seem very similar on account of having little to no manufacturing difference, they do have different advantages when it comes to applications.
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Dry Inlay
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Wet Inlay
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These work best on curved, uneven, and rough surfaces. Applying adhesive separately allows the inlay to better hold onto surfaces contaminated by dust.
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Wet inlays are best suited for plain surfaces like cardboard and paper. They also work well on porous surfaces but may face problems with uneven and curved items.
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Users can apply special adhesives or mix two types of adhesives to provide proper mounting reinforcement against extreme environmental conditions.
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The adhesive layers on these tags may not always be compatible with the weather/environmental conditions and may affect their functioning.
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These are easier to remove from items without damaging the surface, thus, are compatible with clothing, electronics, etc.
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Wet inlays have a strong adhesive layer, which provides them with good permanent mounting. However, it also means that they cannot be removed properly without damaging the surface of the item.
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These can be customized easily when it comes to their size and shape.
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These inlays are constrained by size & shape limitations, as they need proper adhesive surface area to work.
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How Does Radio Frequency Identification Work?
By now you know the surface-level workings of radio frequency identification technology. As noted above, these systems consist of a tag, reader, and antennae. A reader uses the antenna to send continuous signals, creating an interrogation field. The interrogation field can be further divided into two sections, namely: Near-Field, and Far-Field. The system works by receiving information from the tag when they are inside this field. The working principle behind a tag differs based on the type of tag it is.
Passive Systems
These tags consist of a simple inlay, with an outer shell. Once a tag is inside the interrogation zone, it can communicate using two methods, depending on the region of the field. If a tag is in the far field, it uses a method called radiative coupling. In this method, the antenna on the tag receives the radio signals from the reader and essentially reflects a part of the signal. It uses a phenomenon called backscattering to achieve this, the reflected signal also carries the data inside the tag’s chip with it.
If the tag is inside the near-field, it will use a process called inductive coupling. This process works on a phenomenon called electromagnetic induction. Inside the near-field, the radio signals are powerful enough to induce an electric current inside the tag. Once powered up, the tag uses this energy to broadcast a signal using its antenna to transmit the information inside it. This method only works, within 10 cm of the reader.
Active Systems
Unlike passive systems, these tags have an internal power source, mostly a lithium-ion Coin Battery. The tag relies on this battery to power up and broadcast the signal. There are two types of active tags, namely – Beacons, and Transponders. A beacon tag uses the battery to repeatedly broadcast a signal using its antenna. These signals carry the information stored in the tag’s chip. Whenever a reader is inside the broadcasting range of an active tag, it will receive the signal.
A transponder/Battery-Assisted Passive (BAP) Tag, on the other hand, doesn’t continuously broadcast a signal. They use an internal power supply, but they only work when in the field of influence of a reader. When transponder tags enter the interrogation zone of a reader, the antenna receives it and further sends a signal to the battery to power on. The tag then uses the battery and starts sending out signals to the reader. These have a longer lifespan than beacon tags.
Active & Passive Systems: Difference
Since active tags use an internal power supply, their signals have more energy, thus giving them a larger communication range. However, due to this, they also have a limited operational lifespan and need to be discarded or get their batteries changed after 3-5 years. On the other hand, passive tags have virtually no limit to their lifespan and can work as long as there is no physical damage.
Classifications of RFID Tags
There is another way to classify tags, based on the technological standards that go into their manufacturing and operations. Based on these, we can classify RFID tags into 6 different classes.
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Classification
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Functionality/Meaning
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Class 0
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These only refer to pre-programmed passive RFID tags that operate on Ultra-High Frequency.
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Class 1
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These operate on either High Frequency or Ultra-High Frequency. Also, they can only be programmed once (read-only memory).
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Class 2
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Passive RFID tags with read-write capabilities.
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Class 3
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Tags that can be read and re-programmed at any time, with additional onboard sensors like temperature, pressure, and motion. In addition, they can also be BAP or Active.
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Class 4
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Active tags with read-write memory can also communicate with other tags.
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Class 5
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These are the most advanced tags, they are active and capable of communicating with other tags, readers, and other devices. They can also power up other passive tags with their signals.
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Conclusion
Radio Frequency Identification inlays are an essential component of any type of tag, it is responsible for storing and communicating information. Inlays provide exceptional asset identification and tracking capabilities at an extremely affordable cost. There are two types of inlays, wet & dry, with their uses. So, before you select one for your business, read this blog carefully.
Frequently Asked Questions
Q1. What is wet inlay RFID?
Ans - These are a type of RF AIDC devices, that consist of an RFID chip connected to a small antenna, sandwiched between one layer of substrate & a layer of adhesive.
Q2. What is the difference between RFID inlay and tag?
Ans - The only difference between the two is the outer covering, the shell. A tag consists of an RFID inlay, safely nested inside an outer protective shell.
Q3. How many chips are in RFID?
Ans - An RFID tag only has one microchip that holds the data inside it. A tag consists of three components, a chip, an antenna, and a substrate.
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