Measurement of dielectric constant of waxes at different temperatures using split ring resonator structure

Chakyar, Sreedevi P.; Shanto, T A; Murali, Aathira; Simon, Klaus; Paul, Narinder; Andrews, Jolly; Joseph, V. P.

doi:10.1109/imarc.2016.7939638

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Depending on the thickness of the wax film on top of the electrodes, as illustrated in Figure 4a, the electric fields generated by the electrodes in the wax and the surrounding soil are impacted. The dielectric constant of beeswax measured at 3 GHz is 1.8 at 30 °C, 40 which is similar to the reported dielectric constant of dry soil measured at a similar frequency. 41 Therefore, the sensors with encapsulants of different thicknesses should read similar capacitances in dry soil.…”

Section: ■ Introductionsupporting

confidence: 84%

Controlled Biodegradation of an Additively Fabricated Capacitive Soil Moisture Sensor

Sui

Atreya

Dahal

et al. 2021

ACS Sustainable Chem. Eng.

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Successful precision agriculture decision making requires characterizing soil heterogeneity at high spatiotemporal resolution in real-time in order to optimize input (such as water and nutrient) amounts and location. In order to achieve this goal, a printed soil moisture sensor fabricated from biodegradable materials is demonstrated. These devices are intended to function during the growing season and then harmlessly degrade afterward, enabling high-density deployment, eliminating the need for sensor retrieval, and enabling the use of simple device structures and low-cost materials and fabrication techniques. A capacitive structure is used with a water-soluble zinc electrode printed onto a biodegradable substrate. Rapidly degrading substrate and electrode are encapsulated in a slowly degrading wax blend that protects the device, reduces drift, and controls degradation time. A linear capacitance response is observed for soil samples with a volumetric water content from 0 to 72%. Accelerated degradation testing demonstrates that the sensor responds predictably and stably until the encapsulation is breached, at which point the sensor fails rapidly, providing a clear distinction between the functional and nonfunctional lifetimes of the sensor. These results demonstrate the potential of biodegradable sensors to allow maintenance-free, affordable, and real-time soil moisture measurement at high spatial density for precision irrigation control.

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Section: ■ Introductionsupporting

confidence: 84%

Controlled Biodegradation of an Additively Fabricated Capacitive Soil Moisture Sensor

Sui

Atreya

Dahal

et al. 2021

ACS Sustainable Chem. Eng.

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show abstract

“…An insulating oleogel matrix made with the same components, without the activated carbon, has been used as a degradable/digestible matrix for drug encapsulation. The easy processability and the low dielectric constant of sunflower oil and beeswax (≈3 [ 56 ] and ≈2, [ 57 ] respectively), allow the realization of the insulating scaffold. This part of the device has been engineered to trigger the shift between capacitive and galvanic IBC coupling and, simultaneously, enable the drug release.…”

Section: Resultsmentioning

confidence: 99%

Monitoring of Drug Release via Intra Body Communication with an Edible Pill

Lamanna

Cataldi

Friuli

et al. 2022

Adv Materials Technologies

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Oral drug administration provides a convenient and patient‐compliant way for drug delivery, especially for chronic diseases and prolonged pharmacological treatments. However, due to the repetitiveness of such therapeutic approach, the patients are led to neglect/forget the therapy affecting the healthcare delivery. Indeed, the non‐adherence to pharmacological prescriptions and the unknown amount of real‐time drug release result in a non‐compliant therapeutic drug level over the protracted therapies. The proposed technology will enable the monitoring of both pharmacological adherence and real‐time drug release. The approach exploits a passive intrabody communication (IBC) activation in order to enable an edible pill, realized starting from food additives and food‐grade materials, to monitor pharmacological adherence. Following activation, the signal is modulated by IBC coupling switching triggered by pill degradation in a gastrointestinal tract, resulting in a monitored drug release. The proof‐of‐concept is designed for a targeted release and monitoring of Metformin in the intestine. The system shows an in vitro limit of cumulative drug release detection of 18 µg mL−1 and a limit of real‐time drug release detection of 2 µg mL−1 min−1. This platform represents the first solution to monitor passive drug release in real‐time, from intake to complete absorption, enabling unique and long‐sought healthcare therapy and treatment opportunity.

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“…[19][20][21] Metamaterial-inspired sensors are in great demand in various spheres of science owing to their extreme sensitivity and preciseness. 22 Some of the noticeable applications in this realm are: SRR-based sensors for the measurement of complex permittivity of dielectrics 23 and their temperature dependence, 24 vibration sensors capable of detecting seismic waves, 25 near eld imaging probes, 26 non-destructive thickness measurement of dielectric lms, 27 near-eld perturbation studies, 28 micro-uidic sensors, 29 multichannel thin lm sensors, 30 and biosensors. 31 A wire split ring resonator (WSRR), a special SRR structure, consists of two concentric metallic rings with splits oriented in opposite directions.…”

Section: Introductionmentioning

confidence: 99%