and intelligent applications including personalized feedback therapy, fast speech, and visual recognition. [1][2][3][4][5] In particular in the non-conventional space of smart applications requiring conformal attachment on non-flat surfaces such as on-body wearables, the notion of system on plastics (SOP) incorporating neuromorphic computing provides a potential solution. [1,2] To build such a flexible neuromorphic system, the fabrication of memristors equipped with synaptic functions is a key step to forming the artificial neural network. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] However, current memristor manufacturing technologies such as chemical vapor deposition (CVD), [7,8,[11][12][13] spin-coating, [14,15] or entire transfer [16] impose enormous challenges on flexible substrates as they suffer from high temperature, low yield and complex sacrificial layer removal. Efforts in finding low temperature fabrication technique and robust resistive switching (RS) material are essential to equip the SOP with the data storage and processing capability demanded by target applications. The printing technique-a forefront 3D monolithic integration approach-is suitable for high-volume, low-temperature manufacturing on non-conformal surfaces. [22][23][24][25][26][27][28] The printing technique is shown to offer more freedom in the design of Realization of memristors capable of storing and processing data on flexible substrates is a key enabling technology toward "system-on-plastics". Recent advancements in printing techniques show enormous potential to overcome the major challenges of the current manufacturing processes that require high temperature and planar topography, which may radically change the system integration approach on flexible substrates. However, fully printed memristors are yet to be successfully demonstrated due to the lack of a robust printable switching medium and a reliable printing process. An aerosol-jet-printed Ag/MoS 2 /Ag memristor is realized in a cross-bar structure by developing a scalable and low temperature printing technique utilizing a functional molybdenum disulfide (MoS 2 ) ink platform. The fully printed devices exhibit an ultra-low switching voltage (0.18 V), a high switching ratio (10 7 ), a wide range of tuneable resistance states (10-10 10 Ω) for multi-bit data storage, and a low standby power consumption of 1 fW and a switching energy of 4.5 fJ per transition set. Moreover, the MoS 2 memristor exhibits both volatile and non-volatile resistive switching behavior by controlling the current compliance levels, which efficiently mimic the short-term and longterm plasticity of biological synapses, demonstrating its potential to enable energy-efficient artificial neuromorphic computing.

3D monolithic integration of logic and memory has been the most sought after solution to surpass the Von Neumann bottleneck, for which a low-temperature processed material system becomes inevitable. Two-dimensional materials, with their excellent electrical properties and low thermal budget are potential candidates. Here, we demonstrate a low-temperature hybrid co-integration of one-transistor-one-resistor memory cell, comprising a surface functionalized 2D WSe2 p-FET, with a solution-processed WSe2 Resistive Random Access Memory. The employed plasma oxidation technique results in a low Schottky barrier height of 25 meV with a mobility of 230 cm2 V−1 s−1, leading to a 100x performance enhanced WSe2 p-FET, while the defective WSe2 Resistive Random Access Memory exhibits a switching energy of 2.6 pJ per bit. Furthermore, guided by our device-circuit modelling, we propose vertically stacked channel FETs for high-density sub-0.01 μm2 memory cells, offering a new beyond-Si solution to enable 3-D embedded memories for future computing systems.

Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative efforts, scientific breakthroughs can be made sooner and capitalized for the betterment of humanity.

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