Measured propagation loss for capacitive body-coupled communication (BCC) channel (1 MHz to 60 MHz) is limitedly available in the literature for distances longer than 50 cm. This is either because of experimental complexity to isolate the earth-ground or design complexity in realizing a reliable communication link to assess the performance limitations of capacitive BCC channel. Therefore, an alternate efficient full-wave electromagnetic (EM) simulation approach is presented to realistically analyze capacitive BCC, that is, the interaction of capacitive coupler, the human body, and the environment all together. The presented simulation approach is first evaluated for numerical/human body variation uncertainties and then validated with measurement results from literature, followed by the analysis of capacitive BCC channel for twenty different scenarios. The simulation results show that the vertical coupler configuration is less susceptible to physiological variations of underlying tissues compared to the horizontal coupler configuration. The propagation loss is less for arm positions when they are not touching the torso region irrespective of the communication distance. The propagation loss has also been explained for complex scenarios formed by the ground-plane and the material structures (metals or dielectrics) with the human body. The estimated propagation loss has been used to investigate the link-budget requirement for designing capacitive BCC system in CMOS sub-micron technologies.

Realistic estimation of path loss is vital for designing an effective capacitive body-coupled communication system. The estimation based on simplified analytical models, however, results in errors as they do not model capacitive couplers accurately and different body positions. The proposed efficient full-wave electromagnetic (EM) model takes into account the effect of capacitive coupler, electro-physiological properties of tissues in human body, different body positions and environment all together to realistically predict the path loss. A comparison of both approaches is made in this paper, showing the superior performance of the proposed model.

Capacitive body coupled communication (BCC) channel has been modeled as a two-port complex path impedance matrix [Z] which varies as a function of ten different body positions over the frequency range of 1 MHz to 60 MHz. A systematic numerical simulation methodology has been used to estimate [Z] parameters. The estimated complex path impedance [Z] is a symmetric matrix showing BCC channel is a reciprocal network of passive components for given coupler configuration, body positions and frequency range. The estimated complex path impedance has been utilized to determine either input impedance Zin or output impedance Zout to conjugately match to Zs at transmitter or Zl at receiver, respectively for maximum power transfer. It has been found that the resistive matching below 1000 O and inductive matching between 0.5 ï¿œH to 5 ï¿œH on any side of the two ports can meet the conjugate matching requirements for maximum power transfer for the given body positions and frequency range.

A cost-effective concept of silicon-printed hybrid memory label for capacitive body coupled communication (BCC) is discussed in this paperin the context of internet of things (IoT). The strength of a hybrid approach is deliberated after careful review of organic thin film transistors (OTFTs) performance in the existing printed technologies. Further, the performance of battery operated baseband and passband communication architectures have experimentally been demonstrated for an alternate, short range, wireless, machine-to-machine (M2M) communication paradigm for smart phones platform, the capacitive BCC channel. The  operating frequency range is from 100 kHz to 10 MHz for different body positions and printed electrodes configuration/sizes in conjunction with different output drivers. The transmission/reception of signals to the smart phone has been carried out through an SPI and Bluetooth interface to ensure that isolated earth ground conditions were guaranteed for capacitive BCC channel. The BCC passband communication architecture achieves 1 kbps while the digital baseband architecture achieves 100 kbps data rate for 10−2 packet error rate (PER) in the given experimental setup.

The paradigm of computation is currently changing from desktop computing towards ubiquitous computing by interfacing ambulatory devices with mobile phones/platforms. For an efficient implementation, ultra short range wireless network technologies, such as the body area network (BAN), are needed which could avoid the saturation of carrier frequencies, low power dissipation, and the electromagnetic interference. In this work, body coupled communication (BCC) based on capacitive reactive field has been  outlined as an important extension of BAN. It has been experimentally demonstrated as an alternative to traditional short range wireless communication based on radio frequency (RF) technologies. The concept of signal transmission through the capacitive BCC channel is explained using a lumped circuit model which is further supported by electromagnetic (EM) simulations. There are three different communication architectures which have been experimentally demonstrated using discrete electronic components for capacitive BCC channel for data rates between 1 kbps to 100 kbps. The architectures are based on digital baseband communication and passband communication with LC resonant mode driver. The best architecture is based on passband communication which has been demonstrated for reliable ECG measurement in the context of preventive healthcare.

This paper presents an analog receiver front-end design (AFE) for capacitive body-coupled digital baseband receiver. The most important theoretical aspects of human body electrical model in the perspective of capacitive body-coupled communication (BCC) have also been discussed and the constraints imposed by gain and input-referred noise on the receiver front-end are derived from digital communication theory. Three different AFE topologies have been designed in ST 40-nm CMOS technology node which is selected to enable easy integration in today's system-on-chip environments. Simulation results show that the best AFE topology consisting of a multi-stage AC-coupled preamplifier followed by a Schmitt trigger achieves 57.6 dB gain with an input referred noise PSD of 4.4 nV/√Hz at 6.8 mW.

A low power front-end fully differential operational transconductance amplifier (OTA) has been designed in 65 nm CMOS technology which is suitable to receive low data rates upto 300 kbps for capacitive body coupled communication (BCC) channel. The current shunt current mirror OTA topology has been utilized in open loop configuration in the context of digital baseband architecture on the receiver side. The simulated resuts show that OTA achieves unity gain bandwidth (UGBW) of 200 MHz, dc gain of 40 dB, phase margin of 45 degree and rms integrated noise of 130 μV between 10 kHz to 150 MHz for 1.5 pF load capacitance and power consumption of approximately 250 μW. The OTA achieves high CMRR and PSRR (due to positive supply) of more than 120 dB at 100 Hz.