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Three-dimensional (3D) printing is an emerging technique in the field of biomedical engineering and electronics. This paper presents a novel biofabrication method of implantable carbon electrodes with several advantages including fast prototyping, patient-specific and miniaturization without expensive cleanroom. The method combines stereolithography in additive manufacturing and chemical modification processes to fabricate electrically conductive carbon electrodes. The stereolithography allows the structures to be 3D printed with very fine resolution and desired shapes. The resin is then chemically modified to carbon using pyrolysis to enhance electrochemical performance. The electrochemical characteristics of 3D printing carbon electrodes are assessed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3D printing carbon electrodes is much higher than the same sized platinum (Pt) electrode. In-vivo electromyography (EMG) recording, 3D printing carbon electrodes exhibit much higher signal-to-noise ratio (40.63 ± 7.73) than Pt electrodes (14.26 ± 6.83). The proposed biofabrication method is envisioned to enable 3D printing in many emerging applications in biomedical engineering and electronics.

A biologically inspired compound eye system is fabricated for the detection of object motion without the need for sophisticated image processing. The array of the artificial optical unit, called ommatidium, structurally and functionally mimics the natural compound eyes for motion detection. Each artificial ommatidium consists of polymer lenses, a light-guiding polymer cone, a 3D printing cladding, and a light intensity sensor to measure the change of light intensity during motion detection. To simplify the signal processing and improve the system reliability, low-cost light sensors, instead of CMOS/CCD arrays, are used for measuring the light intensity changes caused by object movement. The distance and speed of a moving metal ball of a pendulum were measured using the compound eye system. The measured results agree well with the theoretical analyses. The error between the measured and calculated speed is less than 2%.