# A Portable Optical Sensor for Microplastic Detection: Development and Calibration
## 4 Conclusions  
In conclusion, the development of the sensor prototype presented in this study offers an innovative solution to the pressing issue of microplastic pollution. The integration of mechanical precision, electronic control, and optical sensing enables the effective detection of microplastics, achieving a balance between functionality and accessibility. The following conclusions summarize the main findings, implications, and future opportunities emerging from this work:  
* **Integrated approach:** This study presents a novel sensor prototype that combines precise mechanical design, electronic control, and optical sensing to effectively detect microplastics. The necessity of integrating diverse technological approaches to confront this pressing environmental concern is underscored by the interdisciplinary nature of the study;
* **Controlled testing and future applications:** To ensure accuracy and reproducibility, the prototype was developed and tested in a controlled environment using commercial PLA microplastics. In addition, future applications may include the deployment of the prototype in real-world environments, such as rivers, oceans, or mountains, for on-site detection. This approach should eliminate the need for subsequent visits to collect additional samples if no microplastics are found. As a result, it would help conserve resources and save time;
* **Advanced detection mechanism:** The detection is conducted by directing a light source through the samples and measuring the intensity in volts. This method is a reliable way to identify microplastics through absorbance (\"experimental absorbance\" or \"attenance\") tests. * **Validation and sensitivity:** We measured the prototype's sensitivity and detection limits with absorbance and attenuation equations. We tested the system with commercial PLA microplastics to ensure accuracy. The prototype cannot measure particles as small as FTIR or Raman, but it identifies microplastics in the visible and near-infrared spectrum through light attenuation. It has been validated by comparison with other methods and can process multiple samples efficiently, making it a useful tool for environmental analysis;
* **Technological innovation:** The system uses LEDs with specific wavelengths and a Raspberry Pi 4 to control them. It also includes stepper motors for precise movement, making the setup efficient and accurate. The incorporation of filters serves to eliminate external noise and ensure the accuracy of the measurements. A graphical user interface (GUI) facilitates operations through two modes: microscopy and LED-based detection;
* **Portable and versatile design:** The prototype's modular and portable design allows it to be used in both laboratory and field applications. This flexible approach overcomesthe current limitations of traditional detection methods, such as FTIR and Raman spectroscopy, which are often expensive and less flexible. _Future Research and Expansion_  
In future research, the prototype could be improved in a number of different directions. One possibility is to adapt it for use in environments such as rivers, oceans, and mountains, which would allow direct testing of samples and reduce the need for additional visits if no contamination is found. Another potential direction is to integrate machine-learning algorithms and Adalin networks to enhance classification and detection accuracy. Additionally, creating a database of material fingerprints could help identify microplastics in a larger range of polymers. The contributions of each author to this article can be summarized as follows: [PERSON] was the primary author and contributed to the methodology, software, investigation, and writing. [PERSON] provided writing corrections and curated the data. [PERSON], [PERSON] and [PERSON] contributed significantly to editing, with [PERSON] also contributing ideas. [PERSON] engaged in methodology, data analysis, writing, editing, and supervision. [PERSON] participated in writing, editing, and methodology.