  We propose a power and data transfer network on a conductive fabric material
based on an existing serial communication protocol, Inter-Integrated Circuit
(I2C). We call the proposed network Inter-IC for Wearables (I2We). Continuous
dc power and I2C-formatted data are simultaneously transferred to tiny sensor
nodes distributed on a double-sided conductive textile. The textile has two
conductive sides isolated from each other and is used as a single planar
transmission line. I2C data are transferred along with dc power supply based on
frequency division multiplexing (FDM). Two carriers are modulated with the
clock (SCL) and the data (SDA) signals of I2C. A modulation and demodulation
circuit is designed to enable using off-the-shelf I2C-interfaced sensor ICs.
One significant originality of this work is that a special filter to enable
passive modulation is designed by locating its impedance poles and zeros at
appropriate frequencies. The proposed scheme enables flexible implementation of
wearable sensor systems in which multiple off-the-shelf tiny sensors are
distributed all over a wear.
