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Abstract Nearly all biosensing platforms can be described using two fundamental steps—collection and detection. Target analytes must be delivered to a sensing element, which can then relay the transduced signal. For point-of-care technologies, where operation is to be kept simple, typically the collection step is passive diffusion driven—which can be slow or limiting under low concentrations. This work demonstrates an integration of both active collection and detection by using resonant wireless power transfer coupled to a nanogap capacitor. Nanoparticles suspended in deionized water are actively trapped using wireless dielectrophoresis and positioned within the most sensitive fringe field regions for wireless impedance-based detection. Trapping of 40 nm particles and larger is demonstrated using a 3.5 VRMS, 1 MHz radiofrequency signal delivered over a distance greater than 8 cm from the nanogap capacitor. Wireless trapping and release of 1 µm polystyrene beads is simultaneously detected in real-time over a distance of 2.5 cm from the nanogap capacitor. Herein, geometric scaling strategies coupled with optimal circuit design is presented to motivate combined collection and detection biosensing platforms amenable to wireless and/or smartphone operation.
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Optothermal microbubble assisted manufacturing of nanogap-rich structures for active chemical sensing
Guiding analytes to the sensing area is an indispensable step in a sensing system. Most of the sensing systems apply a passive sensing method, which waits for the analytes to diffuse towards the sensor. However, passive sensing methods limit the detection of analytes to a picomolar range on micro/nanosensors for a practical time scale. Therefore, active sensing methods need to be used to improve the detection limit in which the analytes are forced to concentrate on the sensors. In this article, we have demonstrated the manufacturing of nanogap-rich structures for active chemical sensing. Nanogap-rich structures are manufactured from metallic nanoparticles through an optothermally generated microbubble (OGMB) which is a laser-induced micron-sized bubble. The OGMB induces a strong convective flow that helps to deposit metallic nanoparticles to form nanogap-rich structures on a solid surface. In addition, the OGMB is used to guide and concentrate analytes towards the nanogap-rich structures for the active sensing of analytes. An active sensing method can improve the detection limit of chemical substances by an order of magnitude compared to a passive sensing method. The microbubble assisted manufacturing of nanogap-rich structures together with an active analyte sensing method paves a new way for advanced chemical and bio-sensing applications.
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- Award ID(s):
- 1761132
- PAR ID:
- 10123990
- Date Published:
- Journal Name:
- Nanoscale
- Volume:
- 11
- Issue:
- 43
- ISSN:
- 2040-3364
- Page Range / eLocation ID:
- 20589 to 20597
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9NR05892C
