Immobilization of biosensors in or on a functional material is critical for subsequent device development and translation to wearable technology. Here, we present the development and assessment of an immobilized quantum dot− transcription factor−nucleic acid complex for progesterone detection as a first step toward such device integration. The sensor, composed of a polyhistidine-tagged transcription factor linked to a quantum dot and a fluorophore-modified cognate DNA, is embedded within a hydrogel as an immobilization matrix. The hydrogel is optically transparent, soft, and flexible as well as traps the quantum dot−transcription factor DNA assembly but allows free passage of the analyte, progesterone. Upon progesterone exposure, DNA dissociates from the quantum dot−transcription factor DNA assembly resulting in an attenuated ratiometric fluorescence output via Forster resonance energy transfer. The sensor performs in a dose-dependent manner with a limit of detection of 55 nM. Repeated analyte measurements are similarly successful. Our approach combines a systematically characterized hydrogel as an immobilization matrix and a transcription factor−DNA assembly as a recognition/transduction element, offering a promising framework for future biosensor devices.

A wheel-like electrorheological finishing (ERF) tool for small parts polishing is proposed and thoroughly studied. First, the electrorheological polishing fluid is tested, and its properties suggest usability for electrorheological fluid-assisted finishing. Then, the mathematical removal model of the ERF tool is built employing the conformal mapping method and high-order multipolar moment theory. Finally, a micropattern of trough is fabricated on a slide glass (7 mm wide and 1 mm thick). The trough is 70 nm deep, and its flat bottom is 1.5 m wide (peak to valley of 3.16 nm and root mean square of 1.27 nm); the surface roughness finally achieves 0.86 nm. The results demonstrate the stable machining capability of the ERF tool for miniature parts.

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