**2. Wireless Capsule Endoscopy (WCE) system**

In May of 2000, a short paper appeared in the journal Nature describing a new form of gastrointestinal endoscopy that was performed with a miniaturized, swallowable camera that was able to transmit color, high-fidelity images of the gastrointestinal tract to a portable recording device (Iddan et al., 2000). The newer technology that expands the diagnostic capabilities in the GI tract is capsule endoscopes also known as wireless capsule endoscopy. One example of the capsule is shown in Figure 1.

Fig. 1. Physical layout of the WCE (Olympus, 2010).

The capsule endoscopy system is composed of several key parts (shown in Figure 2): image sensor and lighting, control unit, wireless communication unit, power source, and mechanical actuator. The imaging capsule is pill-shaped and contains these miniaturized elements: a battery, a lens, LEDs and an antenna/transmitter. The physical layout and conceptual diagram of the WCE are depicted in Figure 1 and Figure 2, respectively. The capsule is activated on removal from a holding assembly, which contains a magnet that keeps the capsule inactive until use. When it is used, capsule record images and transmit them to the belt-pack receiver. The capsule continues to record images at a rate over the course of the 7 to 8 hour image acquisition period, yielding a total of approximately 55,000 images per examination. Receiver/Recorder Unit receives and records the images through an antenna array consisting of several leads that connected by wires to the recording unit, worn in standard locations over the abdomen, as dictated by a template for lead placement. The antenna array and battery pack can be worn under regular clothing. The recording device to which the leads are attached is capable of recording the thousands of images

body as a lossy dielectric material absorbs a number of waves and decreases the power of receiving signals, presenting strong negative effects on the microwave propagation. Therefore, the antenna elements should ideally possess these features: first, the ideal antenna for the wireless capsule endoscope should be less sensitive to human tissue influence; second, the antenna should have enough bandwidth to transmit high resolution images and huge number of data; third, the enhancement of the antenna efficiency would

In this chapter the WCE system and antenna specifications is first introduced and described. Next, the special consideration of body characteristics for antenna design (in body) is summarized. State-of-the-art WCE transmitting and receiving antennas are also reviewed.

In May of 2000, a short paper appeared in the journal Nature describing a new form of gastrointestinal endoscopy that was performed with a miniaturized, swallowable camera that was able to transmit color, high-fidelity images of the gastrointestinal tract to a portable recording device (Iddan et al., 2000). The newer technology that expands the diagnostic capabilities in the GI tract is capsule endoscopes also known as wireless capsule endoscopy.

The capsule endoscopy system is composed of several key parts (shown in Figure 2): image sensor and lighting, control unit, wireless communication unit, power source, and mechanical actuator. The imaging capsule is pill-shaped and contains these miniaturized elements: a battery, a lens, LEDs and an antenna/transmitter. The physical layout and conceptual diagram of the WCE are depicted in Figure 1 and Figure 2, respectively. The capsule is activated on removal from a holding assembly, which contains a magnet that keeps the capsule inactive until use. When it is used, capsule record images and transmit them to the belt-pack receiver. The capsule continues to record images at a rate over the course of the 7 to 8 hour image acquisition period, yielding a total of approximately 55,000 images per examination. Receiver/Recorder Unit receives and records the images through an antenna array consisting of several leads that connected by wires to the recording unit, worn in standard locations over the abdomen, as dictated by a template for lead placement. The antenna array and battery pack can be worn under regular clothing. The recording device to which the leads are attached is capable of recording the thousands of images

facilitate the battery power saving and high data rate transmission.

**2. Wireless Capsule Endoscopy (WCE) system** 

One example of the capsule is shown in Figure 1.

Fig. 1. Physical layout of the WCE (Olympus, 2010).

Finally, concise statements with a conclusion will summarize the chapter.

transmitted by the capsule and received by the antenna array. Once the patient has completed the endoscopy examination, the antenna array and image recording device are returned to the health care provider. The recording device is then attached to a specially modified computer workstation (Gavriel, 2000). The software shows the viewer to watch the video at varying rates of speed, to view it in both forward and reverse directions, and to capture and label individual frames as well as brief video clips.

Fig. 2. Conceptual diagram of the WCE.

Since the device received FDA (American Food and Drug Administration) clearance in August 2001, over 1,000,000 examinations have been conducted globally. The 11mm by 26mm M2A capsule is propelled passively, one end of the capsule contains an optical dome with six white Light Emitting Diodes and a CMOS camera that captures 2 images a second (Given Imaging, 2010). These images relayed via a transmitter using a radio frequency signal to an array of aerials from where they are transferred over the wires to a datarecorder. The sensor array allows for continues triangulation of the position of the capsule inside the body of the patient. The accuracy of the capsule location provide by this method was reported to be +/-3 cm (Ravens & Swain, 2002). In December 2004, FDA approved a second type of capsule developed by Given Imaging-the PillCam ESO, which allows the evaluation of esophageal disease. The response to this demand materialized in the development of the pillCam ESO which has the higher frame rate and CMOS cameras positioned at both ends of the capsule. This capsule acquires and transmits seven frames per second from each camera, giving a total of 14 frames per second (Mishkin et al. 2006). Due to the increased frame rate, the capsule battery life is only 20 minutes. In October 2005, Olympus launched a competitor system called EndoCapsule in Europe. The difference lies in the use of a different imaging technology-CCD, which the manufacturers claim is of higher quality (Fuyono, I. 2005). Another feature of EndoCapsule is the Automatic Brightness Control (ABC), which provides an automatic illumination adjustment as the conditions in the GI tract vary. In October 2006, Given Imaging received the CE Mark to market a third capsule-the PillCam COLON though out the European Union. This capsule measures 11mm by 31mm, that is slightly larger than previous products. It captures 4 images a second for up to 10hours. A new feature in Given Imaging capsules is an automatic lighting control (Eliakim et al. 2006; Schoofs et al., 2006). In 2007, PillCam SB2 was cleared for marketing in the US. According to the manufacturers, it offers advanced optics and a wider field of view. PillCam SB2 also captures nearly twice the mucosal area per image. It also provides Automatic Light Control for optimal illumination of each image. In 2009, the second-generation capsule, PillCam COLON2, was cleared by the European Union. The capsule has the ability to adjust the frame rate in real time to maximize colon tissue coverage. To present, Olympus is working on the development of a new generation capsule endoscope, which features magnetic propulsion. Apart from the novel propulsion and guidance system, the capsule designers aim to provide a drug delivery system, a body fluid sampling system and also the ultrasound scan capability. RF System Lab Company announced the design of the new Sayaka capsule (RF System Lab, 2010), which acquires images at a rate of 30 frames per second and generate about 870,000 over an eight hour period of operation. Also, further applications of magnetic fields are presented (Lenaertes & puers, 2006).
