  A liquid filled, low refractive index material inner-coated silica micro-tube
has been proposed and studied as a coupled micro-resonator sensor to greatly
enhance biochemical sensor sensitivity. Its unique coupling phenomenon has been
analyzed and utilized to boost the refractive index sensitivity of the device
to 967nm/RIU. Through optimization of the coupling strength between the two
microresonators, further improvement in refractive index sensitivity up to
1100nm/RIU has been achieved. This mode coupling strategy allows us to design
robust, thick-walled micro-tube sensors with ultra-high sensitivity which is
useful in practical biochemical sensing applications.
