A technology for low-power high data-rate digital capsule endoscopy with human body communication (CEHBC) is presented in this paper. To transfer the image data stably with low power consumption, the proposed system uses three major schemes: Frequency selective digital transmission (FSDT) modulation with HBC, the use of an algorithm to select electrode pairs, and the LineSync algorithm. The FSDT modulation supports high-data rate transmission and prevents the signal attenuation effect. The selection algorithm of the electrode pair finds the best receiving channel. The LineSync algorithm synchronizes the data and compensates for data polarity during the long data transmission section between the capsule endoscope and the receiver. Because all the major functional blocks of the CEHBC transmitter can be implemented as digital logics, they can be easily fabricated using the field programmable gate array (FPGA). Moreover, this CEHBC transmitter can achieve low power-consumption and can support a relatively high data rate in spite of using its clock a few tens of MHz slower. The proposed CEHBC-TXD is the digital portion of the CEHBC transmitter that provides low-power (3.7 mW) and high data-rate (6 Mbps) performance while it supports a high-resolution image (480 × 480 byte) at 3.13 fps.

Human body communications (HBC) has recently emerged as an innovative alternative to the current radio frequency communications for realizing wireless body area networks (WBAN) using the human body as a transmission channel without wired or wireless connections. This study addresses the provision of reliable modeling of the human body as a passage of the electric signal delivery based on the impulse response measurement through the proposal of a measurement setup and signal processing techniques applicable to wearable devices for healthcare and bio-signal acquisition. In the experiments, customized impulse signals were applied to the body using battery-powered devices isolated to the earth-ground for the operating environments of wearable devices. The impulse responses passed through the body were measured considering 52 measurement conditions determined by the device locations from the head to ankle, and the body postures. Body channel transfer functions (BCTFs) for the respective conditions were derived by an adaptive filter approach using an iterative algorithm to minimize the mean squared error between the measured and modeled impulse responses. The channel analysis parameters, such as mean path-loss, root-mean-square delay spread, and mean and maximum excess delays were analyzed based on the measured body impulse responses. In addition, the practical bit-error-rate performance for HBC based on the BCTFs reproducing inter-symbol interference effects caused by the delay spreads of the body channels were explored to verify communication reliability in terms of the transmitter structures adopting digital transmission, sorts of human body channels, data rates, and operating frequencies.

This paper presents an energy management integrated circuit for multiple energy harvesters in wireless body area network applications. The electrical power acquired from a single energy harvester around a human body is limited to micro watts, which is insufficient to drive a wearable electronic device. To increase this small amount, the energy from a number of harvesters has to be combined. By combining the energy from multiple distributed harvesters, each one producing negligible energy, significant energy for wearable devices can be obtained. In designing an energy management circuit for a wearable device, there are two issues to be resolved. The first is related to the power consumption of the circuit, and the second issue is related to the methods needed to manage the wide range of power that occurs as the energy input changes during harvesting. In this paper, an energy management circuit that resolves the two issues above is described. The circuit was integrated using 0.13 µm Taiwan Semiconductor Manufacturing Company complementary metal-oxide-semiconductor technology. The energy management circuit is designed to combine up to three sources of harvested energy with more than 90% operating efficiency over the entire power range of the energy harvested.

An innovative sound transmission system for an intuitive service utilises the human body as a sound transmission medium. By using the human body as a transmission medium, sound generation in the body and sound transmission through the body can be achieved at the same time. Sound generation in the body is based on the nonlinear characteristics of the human body. Two ultrasonic waves with different frequencies produce an audio signal at the difference frequency of the two waves during the propagation process due to the nonlinearity of the body. By substituting a transmission line with the human body, wireless sound transmission is achieved. This system does not require sound transmitters and the sound transmission line required in the conventional earphones. Users can hear sound without sound transmitters and a transmission line by touching the system without making any other noise outside.