We are part of a growing community of researchers who are developing a new class of soft machines. By using mechanically soft materials (MPa Modulus) we can design systems which overcome the bulk-mechanical mismatches between soft biological systems and hard engineered components. To develop fully integrated soft machines-which include power, communications, and control subsystems the research community requires methods for interconnecting between soft and hard electronics. Sensors based upon eutectic gallium alloys in microfluidic channels can be used to measure normal and strain forces, but integrating these sensors into systems of heterogeneous Young's Modulus is difficult due the complexity of finding a material which is electrically conductive, mechanically flexible, and stable over prolonged periods of time. Many existing gallium-based liquid alloy sensors are not mechanically or electrically robust, and have poor stability over time. We present the design and fabrication of a high-resolution pressure-sensor soft system that can transduce normal force into a digital output. In this soft system, which is built on a monolithic silicone substrate, a galinstan-based microfluidic pressure sensor is integrated with a flexible printed circuit board. We used conductive thread as interconnect and found that this method alleviates problems arising due to the mechanical mismatch between conventional metal wires and soft or liquid materials. Conductive thread is low-cost, it is readily wetted by the liquid metal, it produces little bending moment into the microfluidic channel, and it can be connected directly onto the copper bond-pads of the flexible printed circuit board. We built a bridge-system to provide stable readings from the galinstan pressure sensor. This system gives linear measurement results between 500Pa-3500Pa of applied pressure. We anticipate that integrated systems of this type will find utility in soft-robotic systems as used for wearable technologies like virtual reality, or in soft-medical devices such as exoskeletal rehabilitation robots.

.An all-optical digital-to-analog conversion (DAC) scheme based on time-domain pulse spectrum encoding is proposed and experimentally demonstrated. In this approach, the ultrafast optical pulses are first time-broadened and frequency-chirped based on wavelength-to-time mapping and then segmented and power weighted in both time and spectrum domains to produce the multi-band optical carrier. The optical carrier is intensity-modulated by the serial digital inputs to realize the time-domain pulse spectrum encoding. Each spectrum-encoded pulse is then time-compressed to achieve the incoherent weighted intensity summation of digital bits within each word. This approach generates the multi-band optical carrier and achieves the corresponding incoherent intensity summation using all-fiber structure; the system configuration is greatly simplified. Moreover, the time-domain pulse spectrum encoding could efficiently exploit the superwide spectrum resource offered by ultrafast optical pulses and potentially improve the system conversion resolution. A proof-of-concept experiment of a 4-bit DAC system based on time-domain pulse spectrum encoding is carried out, and the obtained results validate the feasibility of the proposed approach. In addition, the system performance in terms of the effective number of bits is investigated.

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