Highly Stretchable High-Performance Silicon Nanowire Field Effect Transistors Integrated on Elastomer Substrates

Materials-Driven Soft Wearable Bioelectronics for Connected Healthcare

In the era of Internet-of-things, many things can stay connected; however, biological systems, including those necessary for human health, remain unable to stay connected to the global Internet due to the lack of soft conformal biosensors. The fundamental challenge lies in the fact that electronics and biology are distinct and incompatible, as they are based on different materials via different functioning principles. In particular, the human body is soft and curvilinear, yet electronics are typically rigid and planar. Recent advances in materials and materials design have generated tremendous opportunities to design soft wearable bioelectronics, which may bridge the gap, enabling the ultimate dream of connected healthcare for anyone, anytime, and anywhere. We begin with a review of the historical development of healthcare, indicating the significant trend of connected healthcare. This is followed by the focal point of discussion about new materials and materials design, particularly low-dimensional nanomaterials. We summarize material types and their attributes for designing soft bioelectronic sensors; we also cover their synthesis and fabrication methods, including top-down, bottom-up, and their combined approaches. Next, we discuss the wearable energy challenges and progress made to date. In addition to front-end wearable devices, we also describe back-end machine learning algorithms, artificial intelligence, telecommunication, and software. Afterward, we describe the integration of soft wearable bioelectronic systems which have been applied in various testbeds in real-world settings, including laboratories that are preclinical and clinical environments. Finally, we narrate the remaining challenges and opportunities in conjunction with our perspectives.

Application of Silicon Nanowire Field Effect Transistor (SiNW-FET) Biosensor with High Sensitivity

As a new type of one-dimensional semiconductor nanometer material, silicon nanowires (SiNWs) possess good application prospects in the field of biomedical sensing. SiNWs have excellent electronic properties for improving the detection sensitivity of biosensors. The combination of SiNWs and field effect transistors (FETs) formed one special biosensor with high sensitivity and target selectivity in real-time and label-free. Recently, SiNW-FETs have received more attention in fields of biomedical detection. Here, we give a critical review of the progress of SiNW-FETs, in particular, about the reversible surface modification methods. Moreover, we summarized the applications of SiNW-FETs in DNA, protein, and microbial detection. We also discuss the related working principle and technical approaches. Our review provides an extensive discussion for studying the challenges in the future development of SiNW-FETs.

High-performance flexible organic field effect transistors with print-based nanowires

Polymer nanowire (NW) organic field-effect transistors (OFETs) integrated on highly aligned large-area flexible substrates are candidate structures for the development of high-performance flexible electronics. This work presents a universal technique, coaxial focused electrohydrodynamic jet (CFEJ) printing technology, to fabricate highly aligned 90-nm-diameter polymer arrays. This method allows for the preparation of uniformly shaped and precisely positioned nanowires directly on flexible substrates without transfer, thus ensuring their electrical properties. Using indacenodithiophene-co-benzothiadiazole (IDT-BT) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8-BT) as example materials, 5 cm2 arrays were prepared with only minute size variations, which is extremely difficult to do using previously reported methods. According to 2D-GIXRD analysis, the molecules inside the nanowires mainly adopted face-on π-stacking crystallite arrangements. This is quite different from the mixed arrangement of thin films. Nanowire-based OFETs exhibited a high average hole mobility of 1.1 cm2 V-1 s-1 and good device uniformity, indicating the applicability of CFEJ printing as a potential batch manufacturing and integration process for high-performance, scalable polymer nanowire-based OFET circuits. This technique can be used to fabricate various polymer arrays, enabling the use of organic polymer semiconductors in large-area, high-performance electronic devices and providing a new path for the fabrication of flexible displays and wearable electronics in the future.

Nanostripe-Confined Catalyst Formation for Uniform Growth of Ultrathin Silicon Nanowires

Uniform growth of ultrathin silicon nanowire (SiNW) channels is the key to accomplishing reliable integration of various SiNW-based electronics, but remains a formidable challenge for catalytic synthesis, largely due to the lack of uniform size control of the leading metallic droplets. In this work, we explored a nanostripe-confined approach to produce highly uniform indium (In) catalyst droplets that enabled the uniform growth of an orderly SiNW array via an in-plane solid-liquid-solid (IPSLS) guided growth directed by simple step edges. It was found that the size dispersion of the In droplets could be reduced substantially from Dcatpl = 20 ± 96 nm on a planar surface to only Dcatns = 88 ± 13 nm when the width of the In nanostripe was narrowed to Wstr= 100 nm, which could be qualitatively explained in a confined diffusion and nucleation model. The improved droplet uniformity was then translated into a more uniform growth of ultrathin SiNWs, with diameter of only Dnw= 28 ± 4 nm, which has not been reported for single-edge guided IPSLS growth. These results lay a solid basis for the construction of advanced SiNW-derived field-effect transistors, sensors and display applications.