Wooden Tongue Depressor Multiplex Saliva Biosensor Fabricated via Diode Laser Engraving

Abstract

Since wood is a renewable, biodegradable naturally occurring material, the development of conductive patterns on wood substrates is a new and innovative chapter in sustainable electronics and sensors. Herein, we describe the first wooden (bio)sensing device fabricated via diode laser-induced graphitization. For this purpose, a wooden tongue depressor (WTD) is laser-treated and converted to an electrochemical multiplex biosensing device for oral fluid analysis. A low-cost laser engraver, equipped with a low-power (0.5 W) diode laser, programmably irradiates the surface of the WTD, forming two mini electrochemical cells (e-cells). The two e-cells consist of four graphite electrodes: two working electrodes, a common counter, and a common reference electrode. The two e-cells are spatially separated via programmable pen-plotting, using a commercial hydrophobic marker pen. Proof-of-principle for biosensing is demonstrated for the simultaneous determination of glucose and nitrite in artificial saliva. This wooden electrochemical biodevice is an easy-to-fabricate disposable point-of-care chip with a wide scope of applicability to other bioassays, while it paves the way for the low-cost and straightforward production of wooden electrochemical platforms.

Use of Biosensors within the Oral Environment for Systemic Health Monitoring—A Systematic Review

“…A total of 2384 studies were identified from the Web of Science search strategy, of which 7 [15][16][17][18][19][20][21] were deemed relevant after reviewing the title, abstract, and full text. A total of four additional articles were included from hand and citation searching [22][23][24][25]. The full search strategy results can be seen in Figure 2.…”

“…Prior to this being a viable utilisation option for routine biosensor use, the impact of eating and drinking on the biosensor sensitivity and longevity must be assessed. Two studies [21,22] had dual purposes by incorporating two biomarker detections within one sensor, which highlights a future opportunity for tailored biosensors dependent on patient-specific health needs. In this review, intraoral biosensors rely upon indwelling electronics in the oral cavity [18,20,26] or short-term contact between external active circuits and saliva-contacting electrodes [15][16][17][21][22][23]25].…”

“…Two studies [21,22] had dual purposes by incorporating two biomarker detections within one sensor, which highlights a future opportunity for tailored biosensors dependent on patient-specific health needs. In this review, intraoral biosensors rely upon indwelling electronics in the oral cavity [18,20,26] or short-term contact between external active circuits and saliva-contacting electrodes [15][16][17][21][22][23]25]. When placed in the oral cavity, it is essential that the instrumenting electronics are protected from the moist environment to prevent corrosion, device failure, and leakage of toxic chemicals [39].…”

“…For commercial viability, it is essential that biosensors are cost-effective; only Koukouviti et al's [22] laser engraved diode laser wooden tongue depressor commented on the cost and ease of fabrication, with the tongue depressor costing < USD 0.1 and USD 55 for the domestic laser engraving. Due to successful biosensor development having the potential for substantial profit generation, it is interesting to query whether further developments have been made in unpublished private companies' research or patent pending research.…”

Green Fabrication and Analytical Application of Disposable Carbon Electrodes Made from Fallen Tree Leaves Using a CO2 Laser

“…The use of CO 2 lasers to create electrochemical sensors is an approach that has several advantages over traditional sensor manufacturing methods. , In this process, a CO 2 laser is used to selectively remove or burn material from a substrate, creating conductive patterns and structures on the surface that can be used to create electrodes or other sensor components. , It can be used to create sensors from a wide range of materials, including metals, ceramics, and polymers, , patterning complex structures, reproducibly, over substrates. In the environmental sense, CO 2 laser pyrolysis is a dry process that does not require solvents or generate waste products. , Using fallen leaves as a substrate and carbon source for developing electrochemical sensors using laser pyrolysis represents a major step toward the development of high-performance, eco-friendly, and cost-effective sensors.…”