Recent advances in microelectronics, microfluidics, and electrochemical sensing platforms have enabled the development of an emerging class of fully integrated personal health monitoring devices that exploit sweat to noninvasively access biomarker information. Despite such advances, effective sweat sampling remains a significant challenge for reliable biomarker analysis, with many existing methods requiring active stimulation (e.g., iontophoresis, exercise, heat). Natural perspiration offers a suitable alternative as sweat can be collected with minimal effort on the part of the user. To leverage this phenomenon, we devised a thin hydrogel micropatch (THMP), which simultaneously serves as an interface for sweat sampling and a medium for electrochemical sensing. To characterize the performance of the THMP, caffeine and lactate were selected as two representative target molecules. We demonstrated the suitability of the sampling method to track metabolic patterns, as well as to render sample-to-answer biomarker data for personal monitoring (through coupling with an electrochemical sensing system). To inform its potential application, this biomarker sampling and sensing system is incorporated within a distributed terminal-based sensing network, which uniquely capitalizes on the fingertip as a site for simultaneous biomarker data sampling and user identification.

Wearable electroenzymatic sensors enable monitoring of clinically informative biomolecules in epidermally retrievable biofluids. Conventional wearable enzymatic sensors utilize Prussian Blue (a redox mediator) to achieve selectivity against electroactive interferents. However, the use of Prussian Blue presents fundamental challenges including: 1) the susceptibility of the sensor response to dynamic concentration variation of ionic species and 2) the poor operational stability due to the degradation of its framework. As an alternative wearable electroenzymatic sensor development methodology to bypass the aforementioned limitations, a mediator‐free sensing interface is devised, comprising of a coupled platinum nanoparticle/multiwall carbon nanotube layer and a permselective membrane. The interface is adapted to develop sensors targeting glucose, lactate, and choline (as examples of informative metabolites and nutrients), showing high degrees of sensitivity, selectivity (against a wide panel of naturally present and diverse interfering species), stability (<6.5% signal drift over 20 h operation), and reliability of sensing operation in sweat samples. By integration within a readout board, a wireless sample‐to‐answer system is realized for on‐body sweat biomarker analysis. This methodology can be adapted to target a wide panel of biomarkers in various biofluids, introducing a new sensor development direction for personal health monitoring.

Recent advances in biomolecular engineering have led to novel cancer immunotherapies with sophisticated programmed functions, including chimeric antigen receptor (CAR) T cells that bind tumor-associated antigens (TAA) to direct coordinated immune responses. Extensive engineering efforts have been made to program not only CAR specificity, but also downstream pathways that activate molecular responses. Collectively, these efforts can be conceptualized as an immunotherapy circuit: TAAs bind the CAR as input signals; intracellular signaling cascades process the binding interactions into transcriptional and translational events; and those events program effector output functions. More simply, this sequence may be abstracted as input, processing, and output. In this review, we discuss the increasingly complex scene of synthetic-biology solutions in cancer immunotherapy and summarize recent work within the framework of immunotherapy circuits. In doing so, a toolbox of basic modular circuits may be established as a foundation upon which sophisticated solutions can be constructed to meet more complex problems. See related article on p. 5.