Micro-ball lens based optical biosensors

A new optical biosensor is proposed and demonstrated using a new microfiber based structure so called micro-ball lens to sense glucose and uric acid concentration in distilled water. The micro-ball lens is formed at the cleaved tip of the microfiber coupler using an arcing technique. In the proposed sensor, the lens acts as a probe while a reflector is used as a target, is immersed into various concentrations of the glucose and uric acid solutions. It is observed that the intensity of the output power decreases linearly as the glucose concentration is varied from 0 % to 20 % with a sensitivity of 0.27 dB / % and a linearity of more than 98%. On the other hand, as the solution concentration of the uric acid varies from 0 to 500 ppm, the received reflected light intensity of the sensor decreases linearly from -58.1 dBm to -67.8 dBm with a sensitivity of 0.02 dB/ppm and a slope linearity of more than 99 %. The stability, high sensitivity and simplicity of the micro-ball lens probe make this new glucose and uric acid sensors are attractive alternative to other optical based sensing techniques.