Tag diversity of inkjet printed body‐worn radio frequency identification integrated medical sticking plasters for wireless monitoring

Abstract

1. Introduction: Radio Frequency Identification (RFID) has found use in areas such as access control systems, point of sale, automatic toll collection, animal tracking, vehicle tracking and immobilization and also in the retail supply chain [1]. For medical applications, RFID technology can be used for patient tracking and safeguarding [2] as well as for equipment inventory management. RFID tags have also been used for physiological monitoring [3].The use of wireless monitoring in a hospital environment aims to improve the efficiency of patient care. Advances have seen the use of RFID technology as a standalone system or in combination with other wireless technologies [4]. Proposed battery-less wireless health sensors [5] will transmit patient vital data and therefore the risks associated with signal outage are high making it important to keep skin mounted RFID tag read failure to a minimum.Human tracking and monitoring can be achieved with RFID chips embedded in the skin [6] however this is very short read range and is inappropriate for non-permanent applications. Alternatively RFID wristbands [7] are widely used but must go on the wrist or ankle and offer only a loose contact to the skin which compromises their use for monitoring. For instance, it may not be optimal for physiological measurements such as heartbeat and pulse which require close skin contact [8]. The use of RFID for medical sensing has also been reported in works such as [9] where an adhesive sensor badge is reported for sensing biomarkers in sweat and in [10] for monitoring surface temperature.Diversity is a technique used in communication systems where alternative transmission mechanisms are introduced to reduce the chance of losing communication (signal outage). In RFID, the chances of successfully reading a tagged object or person are increased if more than one tag is used. This is referred to as tag diversity. In [11] a plaster operating over a few centimetres at the NFC frequency of 13.56 MHz was presented and in [12] the most efficient tag placement for two worn UHF tags communicating with an external reader was studied using 3 mm thick textile slotted patch antennas. The study indicated more than 2 tags of the slotted patch design were required to provide coverage all around the body. Other works such as [13] have sought to improve the performance of on-body RFID tags by using dual tag antenna diversity to reduce the probability of phase cancellation between the RFID reader continuous carrier wave and the backscattered signal from the tag. Diversity is already often implemented at the reader end and in [14] a non-RFID body mounted wireless system utilizes multiple antennas at the off-body base station. While this results in an improvement in outage, it will also lead to an increase in infrastructure

Effect of skin dielectric properties on the read range of epidermal ultra‐high frequency radio‐frequency identification tags

“…There has been an increase in the use of body mounted devices such as radio-frequency identification (RFID) tags and other sensors in recent years. These devices can be used in hospital environments for patient monitoring and tracking [ 1 ] and also as sensors [ 2 ] due to their non-invasive nature. As these devices get more miniaturised and ever closer to the body, it is important to understand their interaction with the human body which is known to have an adverse effect on the wireless performance of electromagnetic devices in close proximity as have been acknowledged in [ 3 , 4 ].…”

Reliability Improvement of RF Identification of Shadowed People in Building Corridors Using Space Diversity

“…In recent years, researchers have dealt with the development of RFID transponders for special applications, including identification of objects made of metallic or liquid materials [2][3][4][5] and identification of people using transponders situated in the vicinity or directly placed on human bodies [6][7][8][9]. On the contrary, [10], [11] deal with the tag diversity of bodyworn antennas in the case that the shadowing effect of identified people is omitted. Further, the sensing of electrical or non-electrical quantities performed using the RFID transponders represents an up-to-date topic as well [12][13][14].…”