Did you know that IDEX Biometrics TrustedBio™ is less expensive than the competition in all configurations with all SEs?

Did you know that IDEX Biometrics TrustedBio™ is less expensive than the competition in all configurations with all SEs? Do you know the difference between off-chip sensors and silicon sensors? Learn why TrustedBio will be the fingerprint sensor of choice for Gen 3 cards.

2021 is going to be an exciting year for biometric cards. Market activity is ramping. Cards using sensors from IDEX Biometrics (IDEX) and our competitors are starting to deploy to customers. These initial cards are Gen 2 cards that were completed last year and passed all the certifications. What is even more exciting is what happens next. Gen 3 cards are coming that will substantially reduce cost, simplify manufacturing and enable mass adoption.

The transition to Gen 3 is moving rapidly ahead. The first Gen 3 cards, Zwipe Pay ONE and Idemia F.Code Gen2, both with TrustedBio from IDEX, are being finalized. Other card manufacturers are evaluating and choosing sensors as they plan their Gen 3 cards. How will card developers select a sensor? What are the differences between sensors? This blog will explain the differences between sensors and the advantages of IDEX TrustedBio and why we believe TrustedBio will be the sensor of choice in Gen 3 cards.

IDEX sensors use off-chip sensing with a polymer substrate. Sounds most unusual. Our competition makes silicon sensors. What do these confusing terms really mean? It is even more confusing when one learns that both types of sensors use silicon ASICs and both sensors use polymer substrates. What is the difference and why is it important? As you will see, TrustedBio is both less expensive and much more capable at the same time.

Let’s start with some definitions and explanations. Off-chip sensing simply means separating, “moving off-the-chip”, the user interface, the part you touch or see, from the ASIC. It is the most common design technology in the electronic industry. Touch screens on cell phones, HDTVs, Apple watch all connect something larger to a small ASIC. It is a very well understood technology, high volume, high reliability, low cost. Without off-chip technology all the products everyone takes for granted, that get better and cheaper year after year, would not exist. Imagine how expensive your cell phone or HDTV would be if the entire screen were a piece of silicon.

What is a polymer substrate? It is just a fancy term for a very thin multi-layer inexpensive flexible circuit board. One of its primary uses is for connecting electronic components. Molded plastic is not a very precise electronic component placement technology. Instead of trying to connect tiny pins on an ASIC directly to wires on a biometric card, the polymer substrate is used to “fan out” small pins to a few large bonding pads. The large pads make it much easier to connect wires and attach the sensor to a card. Both silicon sensors and IDEX sensors use polymer substrates to provide bonding pads. This is one of the reasons why silicon sensors have a ring around the touch sensing surface, to provide space for the bonding pads.

However, at this point, the technologies diverge. IDEX uses the polymer on top, while silicon sensors use it on the bottom. In addition to providing bonding pads, IDEX uses a few more layers to embed a sensing grid to scan the fingerprint.

The designs and assembly might seem complicated but they use standard high volume manufacturing processes. IDEX uses Tier 1 suppliers, TSMC for the ASIC, SPIL and Amkor for sensor assembly and test, so we can rapidly scale to very high volumes and yields. The end result for both types of sensors is a thin module containing an ASIC and a polymer substrate, about ½ mm thick, consisting of multiple layers with a few large bonding pads that are easy to mount in cards.

IDEX TrustedBio

Silicon Sensors

Silicon ASIC location
Below polymerAbove polymer
< 10 sq mm~40 sq mm
Silicon Process
40 nm130 nm
Polymer Usage
Sensing grid & card bonding padsCard bonding pads
Sensing surface
Polymer sensing gridTop surface of ASIC
Sensing Area
90 sq mm36 sq mm
Power optimized ARM processorNone
Energy harvesting and sharing with SENone


Why is it important to separate the touch sensing grid from the ASIC? Because it allows products to follow Moore’s law. The user interface can be optimized for the application. For biometric cards, the sensing area is the size of a fingerprint. At the same time, the ASIC can continue to shrink, consume less power, run faster, have more features and become cheaper all at the same time.

TrustedBio is a 3 rd generation sensor that started several years ago with Gen 1 in 130nm technology, progressed to 65nm for Gen 2 and progressed further to 40nm for TrustedBio. At the same time it has added more functionality and performance. It now has a PMU that can harvest energy from an antenna and simultaneously power an SE. It has a very fast, variable speed, low power ARM MCU with a lot of memory. It has a much faster, very power efficient scan engine. Faster, more power efficient, more features and cheaper, all at the same time. That is the power of Moore’s law. With these features and programmability, TrustedBio is highly configurable providing the lowest cost solution for all card designs.

In its simplest configuration it provides image acquisition very much like a silicon sensor. This is a configuration that a BioSE might use. How does TrustedBio compare? Recently a new version of a silicon sensor was announced that is about 45% smaller than their previous generation. Even with this substantial size and cost reduction, TrustedBio ASIC is more than 4 times smaller making TrustedBio less expensive. This can be observed because the only announced BioSE, by Zwipe/IDEMIA, selected TrustedBio while being fully aware of all the sensors and roadmaps from every sensor company. The new F.Code Gen2/Zwipe Pay ONE will feature TrustedBio.

Let’s explore a different TrustedBio configuration. Card developers are starting to upgrade their Gen 2 cards to low cost Gen 3 cards. Since the new BioSEs are not yet available, they will likely use standard SEs. How does TrustedBio with its PMU and MCU compare in these designs? The options are:


Silicon Sensor

Components Required
Standard SE + passive inlayStandard SE + PMU + extra MCU + active inlay


The choice is clear. This article explains why TrustedBio is the only fingerprint sensor that reduces card cost by eliminating the “other stuff”, a huge cost savings that cannot be achieved with silicon sensors. We support SEs from every major supplier.

When we introduce customers to the technology and performance of TrustedBio they instantly understand that TrustedBio is unlike any other sensor. They immediately understand that it will greatly simplify the card design and drastically reduce cost. That is why TrustedBio is rapidly gaining traction with multiple card designers and suppliers.

TrustedBio has a cost advantage in every card design. It is less costly when paired with a BioSE and provides a much much lower cost solution when paired with standard SEs, which will be the predominant SE for sometime to come. TrustedBio is a disruptive sensor, dramatically cutting costs, simplifying card manufacturing, and providing outstanding biometric performance. No other fingerprint sensor can accomplish these goals. We anticipate that TrustedBio will be the sensor of choice for Gen 3 cards.