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Currently available point‐of‐care systems for body fluid collection exhibit poor integration with sensors. Herein, the design of a disposable device for interstitial fluid (ISF) extraction as well as glucose, lactate, and potassium ion (K+) monitoring is reported on. It is minimally invasive and appropriate for single use, minimizing the risk of infection to the user. This microscale device contains a 3D‐printed cap‐like structure with a four‐by‐four microneedle (MN) array, bioreceptor‐modified carbon fiber (CF)‐sensing surface, and negative pressure convection technology. These features are incorporated within a compact, self‐contained, and manually operated microscale device, which is capable of withdrawing ≈3.0 μL of ISF from the skin. MN arrays applied with an upward driving force may increase the ISF flow rate. Moreover, functionalized CF working electrodes (WE1, WE2, WE3) are shown to selectively detect lactate, glucose, and K+with high sensitivities of 0.258, 0.549, and 0.657 μA μm−1 cm−2and low detection limits of 0.01, 0.080, 0.05 μm, respectively. Ex vivo testing on porcine skin is used to detect the ISF levels of the biomarkers. The microscale device can be a replacement for current point‐of‐care diagnostic approaches.
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Printed Organic Electrochemical Transistors for Detecting Nutrients in Whole Plant Sap
Abstract Low‐cost biosensors that can rapidly and widely monitor plant nutritional levels will be critical for better understanding plant health and improving precision agriculture decision making. In this work, fully printed ion‐selective organic electrochemical transistors (OECTs) that can detect macronutrient concentrations in whole plant sap are described. Potassium, the most concentrated cation in the majority of plants, is selected as the target analyte as it plays a critical role in plant growth and development. The ion sensors demonstrate high current (170 µA dec−1) and voltage (99 mV dec−1) sensitivity, and a low limit of detection (10 × 10−6 m). These OECT biosensors can be used to determine potassium concentration in raw sap and sap‐like aqueous environments demonstrating a log‐linear response within the expected physiological range of cations in plants. The performance of these printed devices enables their use in high‐throughput plant health monitoring in agricultural and ecological applications.
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- Award ID(s):
- 1935594
- PAR ID:
- 10366380
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 8
- Issue:
- 4
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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