Table 4.
Examples of smartphone-based portable Pb-sensing devices
| General components | Mechanism | LOD | Time | Ref. |
|---|---|---|---|---|
| Preprocessing | Selectivity | |||
| Cost | Practical applications | |||
| Smartphone, inkjet-printed objective lens, image processing | Smartphone nano-colorimetry (SNC): single-step sedimentation (yellow sediment) | 1.37 ppb (DI water); 5 ppb (city water) | 10 min | 38 |
| K2CrO4, PDMS; HNO3 | Ba (>100 ppb), CO3 (precipitate) | |||
| Tap water simulating with Pb | ||||
| Smartphone, Paper Strip; UV lamp (365nm); App. (Color recognizer, Xiyi Technology). | Colorimetric paper-based dual-emission carbon dots (CDs) B/R fluorescence ratio (8/1); BCDs (452 nm); RCDs (620 nm), Paper Strip; L-cysteine (Cu Chelation) | 0.58 ppb (solution instrument) | 5 min | 39 |
| 7.03 ppb (solution smartphone) | ||||
| 9.13 ppb (paper strip smartphone) | ||||
| Cu (interfere) | ||||
| Tap and lake water simulating with Pb | ||||
| Smartphone, TFT LCD, App. (Image process & predict) | Colorimetric machine learning algorithm (localized surface plasmon resonance, LSPR) | 0.5 ppb | 30 min. | 40 |
| Gold nanoparticles (GNPs, red to purple) | Tap water (Tehran, Iran) | |||
| River water (Mazandaran, Iran) | ||||
| Zamzam water (Mecca, Saudi Arabia) | ||||
| Smartphone, Optics, LED, Laser diode (405 nM), App. | FRET protein biosensor | 4.7 ppb | 10-60 min | 35 |
| PBS (pH 7.4), ionomycin (5 μM), Tricine (10 mM) to chelate Zn | Zn (interfere) | |||
| USD $544 | Tap water (Taiwan) | |||
| Smartphone, microcontroller, App. Bluetooth, cloud | Whole-copper electrochemical sensor (WCES) chip, Acetate buffer | 14.9045 ppb | 10 min | 41 |
| Lake water (Binya Lake, Haikou city, China) | ||||
| Smartphone, Paper Strip, Laptop, LED, App. | Pb-Alizarin red S (ALS) complex purple color | 30 ppb (LOD) | 1 min | 42 |
| ALS; (color picker application) | Ni (tolerance ratio > 10) | |||
| USD$0.01 | Waste water (electronics factory) simulating with Pb | |||
| Smartphone, LED (365 nm); diffuser; lens; microarray chip; SBR-App. | Smartphone-based reader (SBR) for paper-based microarray | 60 ppb (experiment); | 5 min | 43 |
| Emission carbon dot (CD) | 15.6 ppb (practical application) | |||
| CDs (450 nm) | Pearl River water (five samples) | |||
| USD $180; 130 g | ||||
| Smartphone, Paper Strip, Laptop, LED, App. | RD6G-1 probe with ring opening of the corresponding spirolactam ring | 120 ppb (LOD) | 31 min | 44 |
| RD6G-1 probe, APTES, AuNPs (Color Picker application) | Cu (color change) | |||
| Chicken meat, liver, heart | ||||
| Duck meat and eggs | ||||
| Smartphone, App. | SPR, interparticle plasmon coupling through agglomeration | 1.5 ppm | N.A. | 45 |
| AgNP, DHCA, L-DOPA | ||||
| Water pollution |
Generally, most of the targets are water from various sources. The WHO/EPA standard is no less than 10/15 ppb.
AgNP = silver nanoparticle; DHCA = deep hypothermic circulatory arrest; DI water = De Ion water or deionized water; FRET = fluorescence resonance energy transfer; L-DOPA = levodopa or l-3,4-dihydroxyphenylalanine; LOD = limit of detection; PBS = phosphate buffered saline; PDMS = polydimethylsiloxane; UV = ultraviolet.