Fabricating optical fiber imaging sensors using inkjet printing technology: A pH sensor proof-of-concept

We demonstrate the feasibility of using Drop-on-Demand microjet printing technology for fabricating imaging sensors by reproducibly printing an array of photopolymerizable sensing elements, containing a pH sensitive indicator, on the surface of an optical fiber image guide. The reproducibility of the microjet printing process is excellent for microdot (i.e. micrometer-sized polymer) sensor diameter (92.2 ± 2.2 μm), height (35.0 ± 1.0 μm), and roundness (0.00072 ± 0.00023). pH sensors were evaluated in terms of pH sensing ability (≤2% sensor variation), response time, and hysteresis using a custom fluorescence imaging system. In addition, the microjet technique has distinct advantages over other fabrication methods, which are discussed in detail.