Biological sensory organelles are often structurally optimized for high sensitivity. Tactile hairs or bristles are ubiquitous mechanosensory organelles in insects. The bristle features a tapering spine that not only serves as a lever arm to promote signal transduction, but also a clever design to protect it from mechanical breaking. A hierarchical distribution over the body further improves the signal detection from all directions. We mimic these features by using synthetic zinc oxide microparticles, each having spherically-distributed, high-aspect-ratio, and high-density nanostructured spines resembling biological bristles. Sensors based on thin films assembled from these microparticles achieve static-pressure detection down to 0.015 Pa, sensitivity up to 121 kPa−1, and a strain gauge factor >104, showing supreme overall performance. Other properties including a robust cyclability >2000, fast response time ~7 ms, and low-temperature synthesis compatible to various integrations further indicate the potential of this sensor technology in applying to wearable technologies and human interfaces.

Resisting biomolecule adsorption onto the surface of brain-implanted microelectrodes is a key issue for in vivo monitoring of neurochemicals. Herein, we demonstrate that an ultrathin cell-membrane-mimic film of ethylenedioxythiophene tailored with zwitterionic phosphorylcholine (EDOT-PC) electropolymerized onto the surface of a carbon fiber microelectrode (CFE) not only resists protein adsorption but also maintains the sensitivity and time response for in vivo monitoring of dopamine (DA). As a consequence, the as-prepared PEDOT-PC/CFEs could be used as a new reliable platform for tracking DA in vivo and would help understand the physiological and pathological functions of DA.

In vivo electrochemistry is one powerful strategy for probing brain chemistry. However, the decreases in sensitivity mainly caused by the adsorption of proteins onto electrode surface in short-term in vivo measurements unfortunately render great challenges in both electrode calibration and selectivity against the alternation of proteins. In this study, we observe that the pretreatment of carbon fiber microelectrodes (CFEs) with bovine serum albumin (BSA) would offer a simple but effective strategy to the challenges mentioned above. We verify our strategy for dopamine (DA) with conventionally used CFEs and for ascorbate with our previously developed carbon nanotube-modified CFEs. We find that, in artificial cerebral spinal fluid (aCSF) solution containing BSA, the current responses of the microelectrodes equilibrate shortly and the results for precalibration carried out in this solution are found to be almost the same as those for the postcalibration in pure aCSF. This observation offers a new solution to electrode calibration for in vivo measurements with a technical simplicity. Furthermore, we find that the use of BSA pretreated CFEs to replace bare CFEs would minimize the interference from the alternation of proteins in the brain. This study offers a new general and effective approach to in vivo electrochemistry with a high reliability and a simplified procedure.

Incorporating neuromorphic electronics in bioelectronic interfaces can provide intelligent responsiveness to environments. However, the signal mismatch between the environmental stimuli and driving amplitude in neuromorphic devices has limited the functional versatility and energy sustainability. Here we demonstrate multifunctional, self-sustained neuromorphic interfaces by achieving signal matching at the biological level. The advances rely on the unique properties of microbially produced protein nanowires, which enable both bio-amplitude (e.g., <100 mV) signal processing and energy harvesting from ambient humidity. Integrating protein nanowire-based sensors, energy devices and memristors of bio-amplitude functions yields flexible, self-powered neuromorphic interfaces that can intelligently interpret biologically relevant stimuli for smart responses. These features, coupled with the fact that protein nanowires are a green biomaterial of potential diverse functionalities, take the interfaces a step closer to biological integration.

The discovery of endogenous sulfide in mammalian brain opens up a door to understanding of the physiological function of hydrogen sulfide (HS). The transformation of different forms of sulfide (i.e., S, HS, HS, bound sulfane sulfur, et al.) in various physiological conditions hurdles the direct detection of hydrogen sulfide in vivo. Here, we find that ammineruthenium(III) (Ru(NH)) can catalyze the electrochemical oxidation of free sulfide including HS and HS in a neutral solution (pH 7.4). This property is used to constitute an electrochemical mechanism for selective detection of hydrogen sulfide. By coupling in vivo microdialysis with selective electrochemical detection, we successfully developed an integrated microchip-based online electrochemical system (OECS) for continuous monitoring of free endogenous hydrogen sulfide in the central nervous system (CNS). The microchip-based OECS is well responsive toward hydrogen sulfide with high stability, sensitivity and selectivity. Compared with the existing methods, the OECS does not require offline treatment of brain tissue or adjustment of the detection solutions into acidic or strong basic atmosphere. These priorities essentially enable the system to accurately and reliably track dynamics of hydrogen sulfide in the CNS.