Direct-write shielded cables for improved signal integrity

Direct-writing techniques of printed electronics have great potential within flexible electronics and allow to fabricate circuits on double curved surfaces. In sensor applications it is often necessary to protect the electrical connections between the sensor and the electrical instrumentation against electromagnetic interference (EMI). This is commonly achieved by shielding the interconnects. In this work we focused on fabrication of a shielded cable structure for low-frequency signal integrity in high-precision sensor applications. Semi printed samples, with only some of the layers printed were measured to have an average signal layer resistivity of 3.93 Ωm and an insulation resistivity of 5.25 GΩm. Fully printed samples had an average signal layer resistivity of 6.72 Ωm and an insulation resistivity of 14.7 GΩm. The printed samples demonstrated shielding effectiveness (SE) of -69 dB down to -86 dB. Based on signal-shield capacitance ranging from 85 - 467 pF, the -3 dB cut-off frequency of the signal transfer function ranged from 0.5 to 2.6 kHz. In summary, we demonstrate for the first time a printed coaxial-cable-like structure for low-frequencies between 1 Hz to 10 kHz.