The defining characteristics of a person can be divided into two categories: psychologically and physically. Psychology focuses not only on the mind and behavior of a person but also on their mental, emotional, and social development. Erik Erikson was one of the first scholars to describe adolescent identity problems. Anna Freud worked with many children, unlocking different original forms of their psychological lives. For example, she was the first to describe the phenomenon of "identification with the aggressor" (Ego, 1936). Identifying an individual's physical characteristics can be achieved by capturing fingerprints, palms, hands, retinas, iris, and facial features and then processing them using computers. Biometric systems based on adults' characteristics are known to have performed admirably.
Although biometrics work brilliantly to confirm and identify adults, validating and identifying infants, newborns, and young children with high accuracy is considered a challenge. However, owing to the lack of security operations in the hospitals and the intensive care units, it has become a must to identify newborns, infants, and young children [1]. More than 678 million children worldwide under five years old in 2021 and an average of 345,000 newborns are added to the population daily. Most of those children are in developing countries where there is not any kind of identification. Figure 1 shows the total population under five years old, based on historical estimates and projections through 150 years, starting with 1950, based on The United Nations Mediterranean Fertility Scenario [2].
Children need to be identified in high demand. Children's biometrics are necessary for many emerging applications, such as keeping track of vaccination schedules. Approximately 25 million children under five do not receive essential vaccinations yearly, and nearly 6.6 million may die from vaccine-preventable diseases. Roughly half of the children under five are chronically ill (dwarfism), and almost 14 percent suffer from acute malnutrition in developed countries. Tracking childhood vaccinations; in the developed countries where more than 5 million children die annually of vaccine-preventable diseases [3, 4]. Concerning identifying missing children, more than 800,000 children are lost in the United States annually - a child almost every 40 seconds and preventing infants' babies from swapping in hospitals. In developing countries, changing newborns after birth is a problem due to insufficient maternity ward facilities and hospital overcrowding [3, 5]. Biometrics helped health workers in developing countries find patient records. According to country rules, the United Nations World Food Program (WFP) has helped deliver food to those in need [6].
Most commonly used biometric traits for recognition systems such as fingerprint [7], iris [8], face [9], palmprint [10, 11], and footprint [11, 12] are often focused on adults. Aside from the fact that infants and young children's biometrics have a low rate of accuracy, another thing is that their physical features change as they grow. Consequently, it is unpredictable and subject to rapid change. In addition, some physical biometrics is expected to shift in size [1, 3]. There are several physical biometrics types, shown in Table 1, and their differences. A fingerprint is defined as a mark left on a surface by rubbing the edges of a human finger [13]. The ridgeline structures in newborns are three to five times smaller than in adults. In newborns, the skin has ridges that can easily deform when in contact [14]. The skin condition of oily or wet fingers of younger children and hence the image quality may be influenced by "the habit of sucking their fingers" [15].
The thin annular structure iris in the eye is responsible for controlling the diameter and size of the person. Attention issues and the inability to remain still are necessary to take the image many times. Despite having their heads fixed or closed, they keep moving their eyes and refuse to capture their data [16, 17]. Face recognition is more common; however, it faces many challenges: a change in the reaction, lighting or environment, uncooperative subjects because of constant movement, until the exact moment when the baby is relaxed and calm with eyes open but not crying or moving a lot. In some situations, the capture procedure took nearly 45 minutes to create a comfortable environment for the newborn [18, 19].
A palm print is an acquired image of the palm area [19]. This technique has many limitations; for example, the newborn must hold still during the capture time, which is two minutes. Besides, the results lack variance, and pressure is required on the hand of the newborn to keep it from moving and uncooperative child. Nevertheless, most studies estimated that 1500 PPI (pixel per inch) would be enough to capture print [11, 10]. A footprint is a mark left by a foot on a surface. Biometric recognition technology is the subject of many opinions. Children are identified using a footprint recognition system in many studies. However, two people are needed to gain a print from a child, one to take a picture and one to hold and calm the infant or the child. It is difficult to match infant footprints due to low image capture quality, very small and fragile ridges, and taking an image at the wrong time of the day. The skin begins to dry and crack a few days after birth, and the ridge pattern that can help identify becomes obscured [21].
Table 1
Comparison of using different biometric features to recognize children
Biometric features | Required Object Cooperation | Persistence | Parents' concerns |
Fingerprint | Moderate (Allow the technician to hold the finger of the child) | Potentially High | Moderate |
Iris | High (Opening eyes and staring at the camera) | Potentially High | Major |
Face | Moderate (Staring at the camera with a neutral expression) | Low (facial aging) | Minor |
Palmprint | High (Opening fist and allow the technician to hold the palm and press) | Potentially Moderate | Moderate |
Footprint | High (Removal of the shoes and the socks and allow the technician to hold the foot and press) | Unknown | Minor |
All biometric features have their own challenges; however, some are in common. For example, infants and newborns are uncooperative subjects. They may refuse to open their hands, or eyes, or move their legs. The rapid growth which constantly changes all physical attributes is another additional challenge. One also needs to consider the protectiveness of the parents and the newborn's fragility. Therefore, ergonomics is very important and should be taken into consideration.
The proliferation of biometric features in person identification today has created a promising field that could influence the identification of young children in the future. The development of machine learning techniques, particularly deep learning, opens up a great deal of potential for automating the extraction and classification of features from images. Furthermore, multimodal fusion was shown to enhance the robustness of the recognition system, enabling it to make a recognition decision although one or more biometric features are not successful. The originality of this paper lies in presenting a fusion between fingerprint and iris, which have the most persistence among all biometric traits, as well as demonstrating the Fingerprint Extraction Tool (FPET) for identifying children.
The rest of this paper is discussed in the following order: The related works are discussed in the next section. Then, Section 3 explains the proposed approach (M²BRTPC). Then, Section 4 presents the experimental protocols that have been used. Then, Section 5 shows the results of the proposed approach compared with other related works. Finally, in the end, Section 6 concludes the paper.