Evolution of Finger Vein Biometric Devices in Terms of Usability
In this chapter, the usability of finger vein biometric devices is reviewed and discussed from various viewpoints. Since the usability requirements vary on both the applications and the situations in which the device is used, the requirements need to be carefully reviewed in light of each viewpoint and reflected to the product design.
KeywordsUsability Anti-vandalism Compactness Compliance Durability High throughput Mobility Portability Universal design Universality
The term usability is defined as follows:
the fact of something being easy to use, or the degree to which it is easy to use 
Obviously, most industrial products are designed in light of usability in order to meet users’ various requirements. These requirements are characterised by factors such as use cases, user profiles, security requirements or local regulations. Since all of these requirements cannot be satisfied by a single device, a variety of devices has been developed and provided to the users who can choose the product’s usability features to fit their needs.
Compliance with regulations,
Portability and mobility,
Durability and anti-vandalism,
High throughput and
In the following sections, the first experimental implementation of the finger vein biometric technology with a very primitive user interface is introduced. The details of each usability factor considered at the time of industrialisation of the technology are then reviewed and discussed by illustrating use cases in the real world. The key factors how the usability requirements were achieved in the product design are also discussed later in this chapter.
6.1.1 Early Implementation
As a commercial product, it is important to design the device so that it is accepted by various types of users. This means that the size and shape of the image scanning platen need to be designed to be suitable for the majority of fingers. The length and the thickness of fingers of the target users are collected, and the device is designed so that it can accept more than 90% of the user population.
One of the most successful finger vein devices was developed and released by Hitachi, Ltd. in 2006. The device was designed to be used on desktop computers and connected to a PC via USB cable. The vein images were captured by the infrared camera embedded in the bottom part of the device and the comparison process was executed on the connected PC . Its compact body and the intuitive design were widely accepted and employed for many use cases such as logical access control, physical access control or time and attendance systems. This model became a benchmark for other finger vein devices developed later as well as the origin of the following usability evolutions.
6.1.3 Evolutions of the Finger Vein Biometric Devices
6.2 Compliance with Regulations
6.2.1 Use Case/Background
In some use cases, the authentication/transaction process needs to be compliant with Public Key Infrastructure (PKI) by law or by regulation. Especially in the banking sector, PKI transactions are widely adopted for both corporate and retail online banking and it is necessary to incorporate PKI functionality into the device.
6.2.2 Usability Requirement Details
A smart card reader must be equipped in a single body.
Communications between the biometric reader and the card reader must be secured.
The “Challenge-Response” protocol must be supported.
The RSA signing functionality is required.
The layout of the smart card reader was the most significant challenge for this implementation. In order to protect the communication between the biometric device and the smart card reader, it was necessary to integrate both components in a single tamper-proof enclosure. Attaching a smart card reader on the hood of the scanner was the easiest option; however, this idea was not employed because the increased height and the weight of the upper part of the device reduced the physical stability.
6.3.1 Use Case/Background
One of the most common feedbacks from the users concerns the dimension of the device. Although the H-1 device was made compact, some users find the upper hood relatively bulky especially when compared with fingerprint readers.
6.3.2 Usability Requirement Details
A small and flat form factor with a minimum footprint is needed.
Practical authentication accuracy must be achieved without the hood.
Since the scanning platen is exposed to the outside, the lighting conditions cannot be controlled. The image contrast is largely influenced by the ambient light and the captured finger vein images can be easily saturated under a strong light such as direct sunlight.
Due to the small form factor, the area available for the scanning platen is very limited. On the other hand, the physical finger area to scan needs to be larger than a certain size in order to achieve practical authentication accuracy.
In order to suppress the influence of the uncontrollable ambient light, the enclosure is carefully designed. The finger rest is made narrow so that the entire platen is covered with the presented finger. The enclosure is painted in matt black to avoid any undesirable light reflected on its surface. These measures prevent the ambient light from getting into the camera, which largely contributes to the stable image capturing.
The scanning platen was made smaller than the H-1 device by reducing the marginal area of the captured image. This reduces the tolerance of the finger positioning, which affects the usability; however, the narrow finger rest and the newly designed fingertip stop help users to present fingers in a consistent manner. A couple of notches are added to both sides of the front part so that users can place their index finger and ring finger for better stability.
6.4 Portability and Mobility
6.4.1 Use Case/Background
One of the most preferred features is the portability of the device. It is not difficult to imagine a situation where users need to authorise transaction requests when they are out of office and do not have any office environment.
6.4.2 Usability Requirement Details
The dimension must be compact enough to fit in a pocket.
The device must be powered without a lead.
Cable connections are not appropriate.
In order to reduce the height of the first-generation device H-1, the hood needed to be removed. Since the infrared light source is embedded under the hood, the optical system layout has to be changed. After a careful technical consideration, two infrared LED arrays are placed on both sides of the scanning platen.
In order to produce the illumination powerful enough to penetrate the presented finger, a large-capacity lithium–ion rechargeable battery is employed. For the wireless connectivity with small power consumption, the Bluetooth® Low Energy technology was employed.
6.5 Universal Design
6.5.1 Use Case/Background
Unauthorised cash withdrawals from ATMs with counterfeit cards, stolen cards and stolen PINs became a serious social issue about 15 years ago in Japan. Many account holders used a vulnerable PIN such as a birthday, a phone number and a car registration number and financial institutions were expected to introduce countermeasures to reduce the fraud risk promptly. In response to this movement, many financial institutes in Japan decided to introduce finger vein biometrics for ATM transactions .
6.5.2 Usability Requirement Details
Users need to be able to present their fingers intuitively and straightforwardly without a special training.
Fingers must be always visible through the authentication process.
The shape of the enclosure must be friendly for visually impaired users.
Since the infrared light source was embedded under the hood of the device in the H-1 device, users could not see their fingers whilst having them scanned. In the course of the proof-of-concept study, some users found it uncomfortable or even scary to insert their fingers into the tunnel under the hood. In order to reduce this psychological stress, the hood needed to be removed and the layout of the light source had to be changed to enhance the usability.
The height of the device should be as low as possible so that users on a wheelchair can easily access the bank card reader and the cash outlet over the biometric device. The device shape itself needs to give an intuitive guide to visually impaired users so that they can understand the proper finger positioning only by touching the device.
6.6 Durability and Anti-vandalism
6.6.1 Use Case/Background
In many cases, ATMs are located outdoors to provide users with 24/7 financial services. The environmental conditions of outdoor use cases are much more challenging than indoor use cases.
6.6.2 Usability Requirement Details
The device needs to be operable under severe weather such as rain, snow or direct sunlight.
The enclosure of the device must withstand vandalism.
As ATM users are general public, the balance between the user-friendliness and the durability is a key factor. The open-type finger vein readers are widely accepted in Japan because users feel less psychological stress as described in the previous chapter. In some countries, however, there are not so many users to feel such stresses and the durability has more importance than the psychological factor.
6.7 High Throughput
6.7.1 Use Case/Background
For physical access, control use cases such as entry to an office building or a ticket barrier in a station, the authentication processing time is a critical factor. Instead of holding a proximity ID card to touch in, it is obviously more convenient if users just need to present their fingers on a reader installed at the entrance. This means that the comparison process needs to be done in the identification mode, or also known as one-to-many authentication.
6.7.2 Usability Requirement Details
In the case of office building scenario, the entrance gate is heavily used typically at the time of open and close of business. The access to the building needs to be granted within the time the existing entrance system (e.g. proximity cards) requires. Otherwise, a long queue will develop at the busiest time.
The authentication must be fast enough to accommodate a large number of visitors.
One-to-many authentication functionality is required.
Fingers presented in various manner need to be accepted.
In order to maximise the throughput, i.e. the number of successful entry permissions per unit time, it is necessary to design a physical access control system that does not require users to stop at the gate. This means that finger rests employed for other models to encourage users to position their fingers correctly cannot be used and thus the presented fingers cannot be completely stationary.
6.8.1 Use Case/Background
Biometric authentication is becoming very common in our daily life. One of the most familiar use cases is the logical access control for mobile devices such as smartphones. Biometric modalities such as fingerprint, facial or iris recognitions are widely used; however, these technologies typically require a dedicated sensor, which is a hurdle for smartphone manufacturers in terms of cost.
6.8.2 Usability Requirement Details
The form factor must be comparable to fingerprint sensor modules.
The weight must be minimal for better portability.
The authentication process should not consume a lot of battery power.
The cost must be minimal for general public use.
Miniaturisation has been a long-awaited evolution for finger vein devices. Although it may be technically possible to achieve the form factor, it is hard to be competitive in terms of cost comparing with the existing biometric readers such as capacitive or swipe fingerprint readers.
In this chapter, the user requirements expected for finger vein biometric devices are summarised and reviewed in terms of usability. The backgrounds of the usability requirements are illustrated by quoting real use cases and the product design approaches to satisfy such requirements are discussed. The usability requirements vary over time or by region together with ever-evolving technologies and need to be reviewed time to time in order to satisfy the needs of the mass-market.
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- 1.Cambridge business English dictionaryGoogle Scholar
- 4.Murakami S, Yamaguchi Y, Himaga M, Inoue T (2018) Finger vein authentication applications in the field of physical security. Hitachi Rev 67(5). http://www.hitachi.com/rev/archive/2018/r2018_05/05b04/index.html
- 5.Ratha NK, Govindaraju V (eds) (2008) Advances in biometrics. Springer-Verlag, LondonGoogle Scholar
- 6.Matsuda Y, Miura N, Nonomura Y, Nagasaka A, Miyatake T (2017) Walkthrough-style multi-finger vein authentication. In: Proceedings of 2017 ICCE, 8–10 Jan 2017Google Scholar
- 7.Miura N, Nakazaki K, Fujio M, Takahashi K (2018) Technology and future prospects for finger vein authentication using visible-light cameras. Hitachi Rev 67(5). http://www.hitachi.com/rev/archive/2018/r2018_05/05a05/index.html
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