Rapid prototyping of paper-based electronics by robotic printing and micromanipulation

The fabrication techniques of paper-based electronics have been widely explored in the past two decades, contributing to the wide application of these promising devices in a variety of fields. In this paper, we report a new rapid prototyping technique for constructing paper-based field-effect transistor (FET) biosensors integrating rolled-up semiconductor microtubes. Leveraging robotic printing and micromanipulation techniques, silver ink electrodes are printed on paper and pre-synthesized microtubes are transferred onto a pair of printed electrodes to form a complete FET. Compared with existing fabrication techniques of paper-based electronics that purely rely on printing, the proposed technique is more versatile in that it can rapidly integrate high-performance semiconductor microtubes onto paper substrates. To improve the printing uniformity, a time-shift mechanism is proposed to compensate the ink under-and over-dispersion at the beginning and end of the printing process, repsectively. To realize automated microtube pick-up and transfer, image processing and motion control algorithms are developed to detect positions of the end-effector (a glass needle) and the microtube, and to control motions of the glass needle with minimized human intervention. We demonstrate the effectiveness of the technique by fabricating the designed paper-based devices using bimetallic microtubes and measure their current-voltage characteristics.