Table 1.
Electrochemical biosensors
| Sensor type | Main target | Sensing mechanism | Detection performance | Technical challenges | Future directions | Device integration |
|---|---|---|---|---|---|---|
| Amperometric | Metabolites | Enzymatic reaction | Good sensitivity (180 μA cm–2 mmol–1 for glucose detection)26; medium stability (~1 month)57 | Improvement of stability and sensitivity | Robust and highly sensitive sensors for point-of-care diagnostics in different environments, including wearable sweat monitoring | Portable and wearable |
| Voltammetric | Proteins and nucleic acids | Bio-affinity recognition | Good sensitivity and low LOD (10 fM for insulin44, ~1 pg ml–1 for glycoproteins47,48 and ~100 fM for DNA50); easy reuse44,48 | Simplification and automation of multistep affinity reactions | Simple, rapid, cost-effective biosensing systems by designing automatic fluidics or one-step sensing mechanisms | Portable |
| Potentiometric | Electrolytes | Ion-selective penetration | Good stability (more than 1 month) and medium sensitivity (~60 mV per decade)57 | Miniaturization and flexibility of sensors | Stable all-solid-state sensing electrodes | Portable and wearable |
| Organic electrochemical transistor | Small molecules, proteins and nucleic acids | Bio-affinity recognition | Good sensitivity and low LOD (30 nM for glucose58, 10 pM for DNA62 and 1 pg ml–1 for proteins64) | Batch preparation of sensing electrodes | Batch production and portable data processing systems | Portable and wearable |
| Photoelectrochemistry | Bio-affinity recognition | Good sensitivity and low LOD73 (~1 μM for lactate, ~1 fM for DNA and ~1 pg ml–1 for glycoproteins) | Equipped with a light source | Miniaturized, implantable sensing devices for in vivo applications | Portable and implantable | |
| ECL | Bio-affinity recognition | Good sensitivity (LOD of ~3 pM for microRNA83, microimaging of membrane proteins on single cells85 and sensing of dopamine released by a single cell86) | Efficient ECL reactions and probes; equipped with an ECL collection module | Highly sensitive ECL imaging systems for high-throughput detection and single-cell analysis | Portable and implantable |
ECL, electrochemiluminescence; LOD, limit of detection.