Table 1.
Comparison of MobileLAMP with existing LAMP incubation devices across cost, temperature stability, open-source status, power requirements, and fabrication complexity. Power consumption specifications include wattage (W), voltage (V), and current (A). Fabrication complexity is assessed across five dimensions: 3D printing requirement, CNC machining, custom electronics design, soldering, and programming. Cost values marked with asterisk (*) indicate either partial data or estimated retail prices. NR, not reported in original publication; N/A, not applicable. References are provided in brackets for each device.
Fig 1.
(a) Photograph of the MobileLAMP device with a one Euro coin included for size reference. (b) Exploded view of the computer-aided design (CAD) diagram illustrating the various components of the MobileLAMP. (c) Electrical schematic of the MobileLAMP, featuring the W1209 temperature controller module.
Fig 2.
Electrical and mechanical components required for building the MobileLAMP device: (a) W1209 temperature controller module. (b) thermistor (c) USB cable (d) heater cartridge (e) 100 Ohm resistor (f) heat block (g) 3 mm screw.
Fig 3.
(a) to (e) Computer-aided design (CAD) diagrams of the MobileLAMP’s 3D-printed components designed using OpenSCAD software. (f) Representation of the print orientation of the MobileLAMP’s 3D-printed parts in the CURA slicing software.
Fig 4.
Three-dimensional (3D) printed components of the MobileLAMP using Polylactic Acid (PLA) material.
(a) Bottom portion of the electronic enclosure. (b) Top portion of the electronic enclosure. (c) Tactile switch buttons for the W1209 module. (d) Circular cover for the heat block. (e) Heat chamber lid for the MobileLAMP.
Table 2.
Bill of Materials to construct the MobileLAMP. Note that the cost of these 3D-printed parts is estimated assuming a $22.99 per kg spool of PLA material [33].
Fig 5.
(a) 3D printed part of MobileLAMP’s bottom enclosure. (b) Thermistor is inserted into the slot. (c) Heat block is placed inside the cylindrical chamber of the bottom enclosure. Thermistor wire is held in place using black tape.
Fig 6.
(a) A 3D-printed circular cover is fitted atop the heat block. (b) The heating cartridge is inserted into the heat block and secured in place with a 3 mm screw. (c) The W1209 module is mounted to the enclosure using the mounting pillars.
Fig 7.
(a) Complete the electric connections according to the circuit diagram shown in Fig 1. (b) Insert the 3D-printed button pins into the tactile switches of the W1209. (c) Secure the top cover to the enclosure.
Fig 8.
(a) The top and bottom parts of the MobileLAMP device are secured with tape. (b) The lamp reaction tube is inserted into the heat block. (c) The upper lid part is fixed to the reaction chamber of the device.
Table 3.
List of primers used in colorimetric LAMP for the detection of SARS-CoV-2 and S. Typhi.
Fig 9.
(a) MobileLAMP temperature profile at 65 °C set-point. The x-axis represents Time (min) and the y-axis represents Temperature (°C). Black line is the mean temperature value (three repeats), green shaded region denotes standard deviation from the mean. (b) The power consumption of the MobileLAMP device is measured with USB-A power meter (PAC1934 from Microchip Technology Incorporated), by connecting the power meter between the USB power source and the MobileLAMP. Current consumption of the MobileLAMP (365 mA) is for the 65°C is shown in the inset.
Fig 10.
Detection of SARS-CoV-2 target using colorimetric RT-LAMP using MobileLAMP compared with thermocycler.
In positive LAMP reactions, the pH indicator dye changes from pink (negative) to yellow (positive) due to acid production during DNA amplification. The detection was carried out at 602 copies/μL (second row), 6022 copies/μL (third row) and 60221 copies/μL (fourth row) compared to NTC (no template control, first row). The figure shows results before incubation (left column, all pink) and after incubation, with duplicate samples tested in both thermocycler (middle two columns) and MobileLAMP (right two columns). MobileLAMP successfully amplified the targets as indicated by colour change from pink to yellow, demonstrating equivalent performance to the commercial thermocycler. Note: For colour-blind accessibility, besides the distinct hue and brightness shift from dark pink to lighter yellow, positive reactions appear in the ‘After incubation’ columns for both devices at all target concentrations, while the NTC (first row) remains pink in all conditions.
Fig 11.
Typhi detection. NTC (no template control, left panel with three tubes) showed no colour change (remaining pink), indicating no amplification occurred. The target STY1607 gene at 60221 copies/μL (right panel with three tubes) changed colour to yellow, indicating successful DNA amplification and positive detection. Note: For colour-blind accessibility, besides the distinct hue and brightness shift from dark pink to lighter yellow, the positive results are shown in the right panel (three tubes), while the negative controls are shown in the left panel (three tubes).
Table 4.
Cost-benefit analysis of approaches to address the control requirements.