Stretchable, wearable and highly sensitive strain sensors are vital to the development of health monitoring systems, smart robots and human machine interfaces. The recent sensor fabrication progress is respectable, but it is limited by complexity, low sensitivity and short service life. Herein we present a facile, cost-effective and scalable method for the development of high-performance composite strain sensors and stretchable conductors based on a composite film consisting of graphene platelets (GnPs) and silicon rubber. Through calculation by the tunnelling theory using experimental data, the composite film has demonstrated ideal linear and reproducible sensitivity to tensile strains, which was contributed by the superior piezoresistivity of GnPs having tunable gauge factors 27.7 -164.5. The composite sensors fabricated in different days demonstrated pretty similar performance, enabling the application as a health-monitoring device to detect various human motions from finger bending to pulse. They can be used as an electronic skin, a vibration sensor, and a human-machine interface controller. Stretchable conductors were made by coating and encapsulating GnPs with polydimethyl siloxane to create a composite; this structure allows the conductor to be readily bent and stretched with sufficient mechanical robustness and cyclability.

Advances in wearable, highly sensitive and multifunctional strain sensors open up new opportunities for the development of wearable human interface devices for various applications such as health monitoring, smart robotics and wearable therapy. Herein, we present a simple and cost-effective method to fabricate a multifunctional strain sensor consisting of a skin-mountable dry adhesive substrate, a robust sensing component and a transdermal drug delivery system. The sensor has high piezoresisitivity to monitor real-time signals from finger bending to ulnar pulse. A transdermal drug delivery system consisting of polylactic-co-glycolic acid nanoparticles and a chitosan matrix is integrated into the sensor and is able to release the nanoparticles into the stratum corneum at a depth of~60 µm. Our approach to the design of multifunctional strain sensors will lead to the development of cost-effective and well-integrated multifunctional wearable devices. C 2019, 5, 17 2 of 16the development of mobile devices where increasing functionalities are being integrated into single devices, multifunctional wearable devices [2,10,11] open new tech logical possibilities in areas such as human-machine interaction, health monitoring and drug delivery [12]. For example, a single device might be fabricated which can simultaneously deliver drugs and monitor the physiological response. Despite the clear promise of such multifunctional wearable devices, further improvements related to the fabrication process and cost-effectiveness are needed for their adoption.In terms of materials selection, there have been various approaches utilizing nanomaterials (e.g., silver nanowires [13], carbon nanotubes [14] and chemical vapor deposition (CVD) graphene [15]) as sensing components and elastomeric polymers or textiles as flexible and stretchable substrates [16,17]. Graphene nanoplatelets (GnPs) have been widely used in various polymer nanocomposites because of their superior electrical and mechanical properties [18][19][20]. Each GnP is typically 2-5 nm in thickness and may contain 3-10 graphene layers [21]. Upon reaching the percolation threshold in a matrix, the individual GnP forms a physically connected network where the overall resistance of the nanocomposites becomes limited by the interlayer contact resistance of the GnPs [4,22]. A strategy to reduce the contact resistance is to combine GnPs with silver nanowires (AgNWs). AgNWs employed in this work are around 40 nm in diameter and 20-60 µm in length. Under low strain, nanowires might change wave amplitudes and slide across each other, thus facilitating and maintaining a conducting network to accommodate the strain [23].Transdermal drug delivery is a promising drug delivery strategy to complement the limitations of traditional oral-and injectable-based methods. Transdermal drug delivery might potentially realize convenient and painless drug delivery and a sustained release profile with reduced side effects [24]. Advances in nanotechnology have led to the development of drug nanocarriers whi...

An integrated translational biosensing technology based on arrays of silicon nanowire field-effect transistors (SiNW FETs) is described and has been preclinically validated for the ultrasensitive detection of the cancer biomarker ALCAM in serum. High-quality SiNW arrays have been rationally designed toward their implementation as molecular biosensors. The FET sensing platform has been fabricated using a complementary metal oxide semiconductor (CMOS)-compatible process. Reliable and reproducible electrical performance has been demonstrated via electrical characterization using a custom-designed portable readout device. Using this platform, the cancer prognostic marker ALCAM could be detected in serum with a detection limit of 15.5 pg/mL. Importantly, the detection could be completed in less than 30 min and span a wide dynamic detection range (∼10(5)). The SiNW-on-a-chip biosensing technology paves the way to the translational clinical application of FET in the detection of cancer protein markers.