An ultrahigh sensitive capacitive pressure sensor based on a porous pyramid dielectric layer (PPDL) is reported. Compared to that of the conventional pyramid dielectric layer, the sensitivity was drastically increased to 44.5 kPa −1 in the pressure range <100 Pa, an unprecedented sensitivity for capacitive pressure sensors. The enhanced sensitivity is attributed to a lower compressive modulus and larger change in an effective dielectric constant under pressure. By placing the pressure sensors on islands of hard elastomer embedded in a soft elastomer substrate, the sensors exhibited insensitivity to strain. The pressure sensors were also nonresponsive to temperature. Finally, a contact resistance-based pressure sensor is also demonstrated by chemically grafting PPDL with a conductive polymer, which also showed drastically enhanced sensitivity.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, affecting one in ten people aged over 65 years. Despite the severity of the disease, early diagnosis of AD is still challenging due to the low accuracy or high cost of neuropsychological tests and neuroimaging. Here we report clinically accurate and ultrasensitive detection of multiple AD core biomarkers (t-tau, p-tau 181 , Aβ 42 , and Aβ 40) in human plasma using densely aligned carbon nanotubes (CNTs). The closely packed and unidirectionally aligned CNT sensor array exhibits high precision, sensitivity, and accuracy, evidenced by a low coefficient of variation (<6%), a femtomolar-level limit of detection, and a high degree of recovery (>93.0%). By measuring the levels of t-tau/Aβ 42 , p-tau 181 /Aβ 42 , and Aβ 42 /Aβ 40 in clinical blood samples, the sensor array successfully discriminates the clinically diagnosed AD patients from healthy controls with an average sensitivity of 90.0%, a selectivity of 90.0%, and an average accuracy of 88.6%.

To mimic the tactile sensing properties of the human skin, signals from tactile sensors need to be processed in an efficient manner. The integration of the tactile sensor with a neuromorphic device can potentially address this issue, as the neuromorphic device has both signal processing and memory capability through which parallel and efficient processing of information is possible. In this article, an intelligent haptic perception device (IHPD) is presented that combines pressure sensing with an organic electrochemical transistor-based synaptic device into a simple device architecture. More importantly, the IHPD is capable of rapid and reversible switching between short-term plasticity (STP) and long-term plasticity (LTP) operation through which accelerated learning, processing of new information, and distinctive operation of STP and LTP are possible. Various types of pressure information such as magnitude, rate, and duration were processed utilizing STP by which error-tolerant perception was demonstrated. Meanwhile, memorization and learning of pressure through a stepwise change in a conductive state was demonstrated using LTP. These demonstrations present unique approaches to process and learn tactile information, which can potentially be utilized in various electronic skin applications in the future.

Integration of rigid components in soft polymer matrix is considered as the most feasible architecture to enable stretchable electronics. However, a method of suppressing cracks at the interface between soft and rigid materials due to excessive and repetitive deformations of various types remains a formidable challenge. Here, we geometrically engineered Ferris wheel–shaped islands (FWIs) capable of effectively suppressing crack propagation at the interface under various deformation modes (stretching, twisting, poking, and crumpling). The optimized FWIs have notable increased strain at failure and fatigue life compared with conventional circle- and square-shaped islands. Stretchable electronics composed of various rigid components (LED and coin cell) were demonstrated using intrinsically stretchable printed electrodes. Furthermore, electronic skin capable of differentiating various tactile stimuli without interference was demonstrated. Our method enables stretchable electronics that can be used under various geometrical forms with notable enhanced durability, enabling stretchable electronics to withstand potentially harsh conditions of everyday usage.

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