The quality monitoring of paracetamol medicament using a noninvasive microwave sensor

Abstract

Environmental conditions, including temperature, humidity, and light, can impact the quality of drugs. Microwave-based approaches offer a fast and cost-effective way to detect quality variations, providing an alternative to traditional techniques in the pharmaceutical and cosmetic industries. This article proposes the use of a microwave sensor for monitoring the quality of pharmaceutical drugs at distinct temperature levels. A small planar sensor based on three hexagonal split ring resonators (TH-SRR) is fabricated. The design is manufactured on an FR-4 dielectric substrate. The sensor is tested on a 1000 mg paracetamol tablet, at temperatures ranging from 40 to 80 [Formula: see text]C. The Variation in the permittivity that characterizes product degradation is translated into a shift in the frequency of the scattering matrix elements. To validate the microwave approach, drug quality is examined with the laser-induced breakdown spectroscopy (LIBS) technique, an optical emission laser used for both qualitative and quantitative investigations of elements contained in a sample. The existing elements are classified using the National Institute of Standards and Technology (NIST) database and categorized according to their spectral line wavelengths. The experiments show the presence of optimal wavelength values for carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) at 247.92 nm, 656.49 nm, 244.23 nm, and 777.48 nm, respectively. The microwave experimental results show a shift frequency of approximately 1 MHz on average when the tablet is heated at 80 [Formula: see text]C for 15 min. Meanwhile, the LIBS measurement shows a remarkable shift in terms of intensity of approximately 8884 and 812 for carbon and hydrogen, respectively. Understanding how paracetamol dries under high temperatures and improving the process settings of the microwave sensor are investigated and assessed in this work.

Figure 1

Setup used for microwave measurement.

Figure 2

Definition of microwave quality shifting $Q_{\mathit{uW}}$.

Figure 3

(a) Top view and (b) Cross-sectional view of the sensor. (Length L = 60 mm, width W = 60 mm, thickness h = 1.6 mm, mutual coupling distance a = 9 mm, resonator’s side s = 4.6 mm, diagonal length d = , gap g =  and path width p = 0.4 mm).

Figure 4

Full-wave simulation of the electric field distribution $\overrightarrow{E}$ in the upper surface plane for individual and array of resonators setups at 3.48 GHz with and without drug samples.

Figure 5

Full-wave simulation of unloaded TH-SSR sensor for (a) split gap variation from g = 0.4 mm to 0.8 mm, with c = 1 mm; (b) coupling distance variation from c = 1 mm to 2 mm, with g = 0.8 mm.

Figure 6

Sensitivity of the TH-SSR based sensor versus the different value of the real part of permittivity ${\epsilon }^{{}^{\prime }}$.

Figure 7

(a) Experimental setup, (b) simulated (solid line) and measured (dashed line) result of the unloaded sensor.

Figure 8

Measured result (solid line) of the loaded sensor with holder. The dashed line presents the measured results of the unloaded sensor with the holder.

Figure 9

(a) Resonance frequency of the sensor versus magnitude of $S_{21}$, as temperature is decreased from 80 to 27 ${}^{\circ }$C. (b) Comparison between resonance frequency versus magnitude of $S_{21}$ before and after heating at 27 ${}^{\circ }$C.

Figure 10

(a) Microwave quality shifting $Q_{\mu W}$ versus heating period at 80 ${}^{\circ }$C, (b) Average microwave quality shifting $Q_{\mu W}$ versus temperature for 3 different paracetamol tablets.

Figure 11

Comparison of different heating temperature (80 ${}^{\circ }$C, 60 ${}^{\circ }$C and 40 ${}^{\circ }$C).

Figure 12

(a) LIBS spectra of the samples used in the study. (b) Drug location in LIBS.

Figure 13

Different peaks for each detected element.

Figure 14

Comparison between $Q_{\mu W}$ and $Q_i$ for (a) Carbon (b) hydrogen.