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This study reports a class of wireless, lightweight, and multifunctional chemical sensors for detection of biomarkers. 

Abstract Physically transient forms of electronics enable unique classes of technologies, ranging from biomedical implants that disappear through processes of bioresorption after serving a clinical need to internet-of-things devices that harmlessly dissolve into the environment following a relevant period of use. Here, we develop a sustainable manufacturing pathway, based on ultrafast pulsed laser ablation, that can support high-volume, cost-effective manipulation of a diverse collection of organic and inorganic materials, each designed to degrade by hydrolysis or enzymatic activity, into patterned, multi-layered architectures with high resolution and accurate overlay registration. The technology can operate in patterning, thinning and/or cutting modes with (ultra)thin eco/bioresorbable materials of different types of semiconductors, dielectrics, and conductors on flexible substrates. Component-level demonstrations span passive and active devices, including diodes and field-effect transistors. Patterning these devices into interconnected layouts yields functional systems, as illustrated in examples that range from wireless implants as monitors of neural and cardiac activity, to thermal probes of microvascular flow, and multi-electrode arrays for biopotential sensing. These advances create important processing options for eco/bioresorbable materials and associated electronic systems, with immediate applicability across nearly all types of bioelectronic studies. 

Abstract Chemical biomarkers in the central nervous system can provide valuable quantitative measures to gain insight into the etiology and pathogenesis of neurological diseases. Glutamate, one of the most important excitatory neurotransmitters in the brain, has been found to be upregulated in various neurological disorders, such as traumatic brain injury, Alzheimer's disease, stroke, epilepsy, chronic pain, and migraines. However, quantitatively monitoring glutamate release in situ has been challenging. This work presents a novel class of flexible, miniaturized probes inspired by biofuel cells for monitoring synaptically released glutamate in the nervous system. The resulting sensors, with dimensions as low as 50 by 50 μm, can detect real‐time changes in glutamate within the biologically relevant concentration range. Experiments exploiting the hippocampal circuit in mice models demonstrate the capability of the sensors in monitoring glutamate release via electrical stimulation using acute brain slices. These advances could aid in basic neuroscience studies and translational engineering, as the sensors provide a diagnostic tool for neurological disorders. Additionally, adapting the biofuel cell design to other neurotransmitters can potentially enable the detailed study of the effect of neurotransmitter dysregulation on neuronal cell signaling pathways and revolutionize neuroscience.