Recent Trends in Self-Powered Photoelectrochemical Sensors: From the Perspective of Signal Output

A novel electrocatalytic current dominated self-powered photoelectrochemical sensor based on patterned bipolar electrode

BACKGROUND

Self-powered photoelectrochemical (sPEC) sensors display significant potential in clinical diagnosis and health evaluation. Until now, most of sPEC sensors rely on individual or dual photoelectrodes systems, which still suffer from drawbacks arising from cross-interference in real sample tests.

RESULTS

Herein, we combined the spatial isolation merit of a closed bipolar electrode (cBPE) with a self-powered photoelectrochemical method to develop a new-type of cBPE-sPEC sensor. Our results demonstrate that crystalline polymeric carbon nitride (CPCN) and Pt nanoparticles (Pt NPs) can be selectively deposited on a patterned carboxylated single-walled carbon nanotube (SWCNT) film to fabricate bipolar sensors via a vacuum filtration-assisted deposition technique. Under photoirradiation, the photoanode drives the electrocatalytic reactions at both ends of cBPE, forming a current loop, and the presence of H2O2 enhances the photocurrent response via an improved electrocatalytic current on cBPE. As proof of concept, the enzyme-based glucose sensor was developed to showcase the practicability of the cBPE-sPEC sensor.

SIGNIFICANCE AND NOVELTY

We believe that the new type photoelectrochemical sensing mechanism regulated by electrocatalytic current would facilitate the widespread application of cBPE-sPEC sensor in various biological analysis.

Self-powered PEC platform with large and stable photocurrent for blocker-free sensitive assay of Caspase-3 activity based on CdIn2S4/CdS QDs anode and NH2-MIL-125(Ti)@MAPbI3/Au NPs cathode

The diagnosis of apoptosis is of particular importance for assessing apoptosis-related disease progression and improving the therapy efficiency. Caspase-3 is the most frequently activated cysteine protease and a key mediator of cell apoptosis, therefore, its activity assay is vital. Here, by encapsulating of MAPbI3 in NH2-MIL-125(Ti) and constructing "Z-scheme" structure between CdIn2S4 microspheres and CdS quantum dots (QDs) to obtain high-photoelectrochemical (PEC)-stability and large-photocurrent NH2-MIL-125(Ti)@MAPbI3/Au NPs photocathode and CdIn2S4/CdS QDs photoanode, respectively, a new dual-photoelectrode self-powered PEC platform was constructed for highly sensitive and blocker-free assay of caspase-3 activity. The designed negatively-charged CC-DEVD-peptide chains were immobilized on the positive-charged NH2-MIL-125(Ti)@MAPbI3/Au NPs hybrids in flat-lying state due to the electrostatic interaction and double Au-S bonds to maximally suppress the photocurrent signal and to make blockers be not needed. When caspase-3 was present, the CC-DEVD-peptide chains were specifically recognized and cleaved, and only a short Cys-Cys dipeptide remained on the NH2-MIL-125(Ti)@MAPbI3/Au NPs/ITO photocathode, leading to an obviously enhanced photocurrent. Due to the good PEC properties and the matched energy levels of CdIn2S4/CdS QDs and NH2-MIL-125(Ti)@MAPbI3/Au NPs, the developed dual-photoelectrode self-powered PEC platform had large open circuit voltage and photocurrent, and the caspase-3 activity was sensitively assayed (linear range, 0.1 pg mL-1 - 1.0 μg mL-1; detection limit, 5.7 fg mL-1), implying its promising applications in assessment of disease progression and therapy efficiency associated with apoptosis, and rapid screening of caspase-3-related drugs.

Dual-mode colorimetric/photoelectrochemical sensing platform derived from the decomposition of CuHPT for glutathione detection

The development of integrated dual signal outputs for the reliable and accurate determination of glutathione (GSH) is highly significant for its key role in physiological processes. Herein, a colorimetric/photoelectrochemical (PEC) dual-mode sensing platform was constructed based on the GSH-triggered decomposition of a copper-organic framework (CuHPT). A hollow nanostructured type-II heterojunction of CoS/In-CdS was synthesized using an imidazolate framework (ZIF-67) as a template. CuHPT was decomposed in the presence of GSH to form catechol ligands and Cu+, enabling dual-mode sensing. An ion exchange reaction between the produced Cu+ and Cd2+ of CoS/In-CdS resulted in the formation of Cu2S, causing a decrease in the photocurrent and the sensitive detection of GSH. Cu+ catalyzed H2O2 to produce ˙OH via a Fenton-like reaction, achieving colorimetric sensing. The proposed dual-mode sensor based on the target-triggered decomposition of CuHPT exhibited linear responses for colorimetric and PEC sensing of GSH in the range of 0.05-1.20 mM and 0.5-800 μM with the limit of detections (LODs) of 18 μM and 0.11 μM, respectively. The reliable determination of GSH in human serum provides a new possibility for the application of the present dual-mode sensor in clinical assays.

A Bi13S18I2-based wearable photoelectrochemical biosensor for accurate monitoring of L-tyrosine in sweat as a diabetes biomarker

The development of real-time, non-invasive, flexible wearable systems for biomarker monitoring is critical for advancing healthcare diagnostics. Herein, we present a flexible patch consisting of an ultrasensitive photoelectrochemical (PEC) biosensor integrated with a hydrophilic nonwoven fabric sweat-collecting pad for precise, unbiased, and high-performance monitoring of L-tyrosine (L-Tyr) in sweat. The innovative PEC sensor is based on the incorporation of Bi13S18I2 (BSI) as a photosensitive material, combined with a molecularly imprinted poly(m-phenylenediamine) (MIP) matrix as a biorecognition element. The developed biosensing photoelectrode exhibits an enhanced photoanodic response and improved incident photon-to-current efficiency (IPCE), attributed to optimized energy band alignment, increased visible-light absorption, efficient photo-induced charge separation, and transfer, extended electron-hole pair lifetime, and enhanced electron density and mobility. The platform offers an impressive linear detection range of 80 nM to 350 μM, with a detection limit as low as 24 nM, ensuring accurate and reliable L-Tyr monitoring, which is essential for diabetes care. The sensor exhibited high repeatability, long-term stability, and low cross-reactivity with potential interfering substances, further demonstrating its practicality for use in complex biological environments. This work marks a significant advancement in wearable diagnostic technology, providing a versatile platform for non-invasive biomarker monitoring. The ability to accurately detect L-Tyr in sweat makes this sensor a valuable tool for real-time health monitoring and diagnostics, opening new avenues for future innovations in PEC sensing and biosensing technologies.

Acetylcholinesterase-assisted photoelectrochemical solution gated graphene field-effect transistor for organophosphates pesticide detection

This study develops a photoelectrochemical solution-gated graphene field-effect transistor (PEC-SGGT) for ultrasensitive organophosphates (OPs) detection, merging optoelectronic modulation with enzymatic signal amplification. The sensor employs a hybrid system of cadmium sulfide quantum dots (CdS QDs) and acetylcholinesterase (AChE), using acetylthiocholine (ATCh) as the substrate. Under light, CdS QDs generate electron-hole pairs, while AChE hydrolyzes ATCh into thiocholine (TCh), which enhances charge separation and amplifies photocurrent. OPs-induced inhibition of AChE reduces TCh production, decreasing photocurrent and enabling PEC-SGGT gate-controlled OPs quantification. The sensor achieves a detection limit of 0.21 pM and a linear range of 0.1 nM to 1 mM. This work demonstrates the potential of light-assisted, enzyme-functionalized, gate-modulated PEC-SGGT systems for diverse biosensing applications, including enzymatic sensors, enzyme-labeled immunosensors, and enzyme-labeled DNA biosensors, advancing bioelectronics.

Target-assisted self-powered photoelectrochemical sensor based on Ag2S/BiOCl heterojunction for ultrasensitive chlorpyrifos detection

Chlorpyrifos (CPF), a widely used organophosphorus pesticide, presents substantial risks to both environmental and human health due to its persistent accumulation, thereby necessitating the development of effective detection methods. Self-powered photoelectrochemical (PEC) sensors, as an innovative technology, address the limitations inherent in conventional sensors, such as susceptibility to interference and inadequate signal response. Herein, we synthesized Ag2S/BiOCl as a photosensitive material, employing it as a light-harvesting substrate and a signal-transducing platform to develop a self-powered PEC sensor for the detection of CPF. Ag2S/BiOCl composite exhibited a markedly enhanced photocurrent response in comparison to either Ag2S or BiOCl individually. CPF possesses distinctive chemical bonds, and upon incubation on the electrode surface, it forms chelates with Bi (III) within the Ag2S/BiOCl heterojunction. This interaction effectively impedes the transfer of photogenerated charges, resulting in a pronounced decrease in the original PEC signal, thereby facilitating the rapid and sensitive detection of CPF. This self-powder PEC sensor exhibited excellent linearity over the concentration range of 10.0 pg mL-1-100.0 ng mL-1, with a detection limit of 1.5 pg mL-1. The successful application of this work in real samples highlights its strong potential for monitoring of CPF residues, while also demonstrating its broader applicability for detecting other contaminants.

GDH-TiO2NFs-rGO photoelectrode: A novel photoelectric chemobiosensor for lipase activity detection

In the grain industry, lipases can hydrolyze the oils and fats in grains into glycerol and fatty acids, causing grain rancidity. If not detected and controlled, it would lead to the waste of grains and resources. In this research, rice bran was taken as the research object and a nanocomposite material with photoelectric activity, TiO2NFs-rGO, was developed by electrospinning technology. After immobilizing GDH enzyme, a photoelectrochemical biosensor, GDH-TiO2NFs-rGO-ITO, was constructed. When the glycerol content was within the range of 0.025-7 mmol/L, the photoelectric signal generated by the biosensor exhibited a favorable linear relationship with the glycerol content. The detection limit (S/N = 3) was 0.043 U/mL Even after seven uses, the detection of lipase activity still demonstrated high reproducibility. After being stored for 20 days, the photoelectric response value could still reach 81.37 % of that on the first day, indicating excellent storage stability. Moreover, other interfering substances in the test base solution did not generate obvious photoelectric responses, demonstrating high anti-interference ability. This biosensor indirectly, rapidly, and accurately detected lipase activity in rice bran. This study paves the way for the quality detection of rice bran during the storage period. In the future, it can be extended to the field of grain quality detection.

A visual COD sensor based on the magnetically oriented graphite flake-enhanced photoelectrochromic effect

A visual chemical oxygen demand (COD) sensor was developed by electrodepositing Prussian blue (PB) on indium tin oxide (ITO) conductive glass to form an electrochromic layer, followed by the vertical alignment and immobilization of graphite flakes under a magnetic field. A TiO₂/g-C₃N₄ heterojunction photocatalyst was in situ integrated with the graphite flakes to enhance the performance. Under the irradiation of visible light, reductive substances in the water sample are oxidized by photogenerated holes from TiO₂/g-C₃N₄, while photogenerated electrons are conducted through the graphite flakes to the electrochromic layer, reducing PB to Prussian white (PW) and causing a color change. The RGB values of the captured image are used to calculate the total color difference, enabling visual quantification of COD. The overlapping of the photo-oxidation layer (POL) and the electrochromic reduction layer (EDL) shortens electron transport distances. Vertically aligned graphite flakes further reduce electron transport resistance, improving photogenerated electron efficiency and lowering the COD detection limit. Additionally, the alignment increases the sensor's effective light-capture area and the photocatalyst loading capacity, expanding the measurement range to 3.2-320 mg/L. The sensor can be easily regenerated by simple cleaning and air oxidation within 1 h, allowing repeated use without interference from chloride ions. The relative standard deviation for repeated measurements and the relative error compared to standard methods are both around 10%, demonstrating good practical applicability.

Plasmonic Graphene-Gold Nanostar Heterojunction for Red-Light Photoelectrochemical Immunosensing of C-Reactive Protein

The development of red-light photoelectrochemical (PEC) nanoimmunosensors offers new avenues for detecting clinically relevant biomarkers with high sensitivity and specificity. Herein, the first PEC nanoimmunosensor based on a plasmonic graphene and gold nanostar (AuNS) heterojunction excited with 765 nm red light is presented for label-free detection of C-reactive protein (CRP), a key biomarker of inflammation. This platform leverages the unique localized surface plasmon resonance effect of AuNSs in combination with in situ generated graphene to enhance photoelectrical conversion efficiency under 765 nm monochromatic light. This wavelength minimizes photodamage and interference from biological samples. By optimizing the nanoarchitecture and utilizing a bifunctional photoactive transduction platform, a linear detection range of 25-800 pg/mL is achieved, with a limit of detection as low as 13.3 pg/mL. The low-energy red-light activation, effective electron-hole pair separation, and signal amplification allow CRP's rapid, selective, and sensitive detection in real clinical samples from patients with low-grade chronic inflammation. The nanoimmunosensor demonstrated consistent analytical performance across multiple samples, showing potential for accurate biomarker monitoring in inflammatory disorders. This work highlights plasmonic nanomaterials to develop robust PEC immunosensors that provide scalable, noninvasive, automated, low-background noise as a highly sensitive alternative for clinical diagnostics.

Self-powered photoelectrochemical sensor based on molecularly imprinted polymer-coupled CBFO photocathode and Ag2S/SnS2 photoanode for ultrasensitive dimethoate sensing

Dimethoate (DIM) is one of the most extensively applied organophosphorus pesticides (OPs), which is used to boost farm productivity due to its high insecticidal efficacy. However, the excessive use of DIM can result in the extensive contamination of soil, groundwater and food. Monitoring of DIM in environmental and food samples is crucial in view of its potential health risks and environmental hazards from excessive residues. The expensive equipment and complex operations for current detection methods greatly limit their practical applications. Herein, a self-powered photoelectrochemical (PEC) sensing platform based on Ag2S/SnS2 photoanode, iron-doped cobalt borate (CBFO) photocathode, and molecularly imprinted polymers (MIPs) was proposed for the detection of DIM. The molecularly imprinted polymers at CBFO photocathode endow the self-powered PEC sensor with high selectivity. The Ag2S/SnS2 photoanode enhances the efficient of electron transfer between the photoanode and photocathode, contributing to the high sensitivity of PEC sensor. The self-powered molecularly imprinted PEC sensor exhibits outstanding sensitivity and selectivity for DIM at concentrations from 1 × 10-2 to 1 × 105 nM with a detection limit of 5.9 pM. Excellent recoveries (95.4 ± 2.6 %, 98.4 ± 2.3 %, 106.3 ± 3.3 %) were achieved in spiked crown pear samples, indicating that the molecularly imprinted PEC sensor is capable of detecting DIM in real samples. This research provides a novel simple, fast, highly selective and sensitive self-powered molecularly imprinted photoelectrochemical sensing platform for detection of DIM. The fabricated PEC sensor offers a promising candidate for the detection method of organophosphorus pesticides residues, which is of great significance for the fields of food safety and environmental protection.

A Chemical Redox Cycling-Based Dual-Mode Biosensor for Self-Powered Photoelectrochemical and Colorimetric Assay of Heat Shock Protein

To advance the biological understanding of heat shock protein (HSP) in different types of cancers, it is crucial to achieve its accurate determination. Herein, a dual-mode self-powered photoelectrochemical (PEC) and colorimetric platform was proposed by integrating enzymatic catalysis and a chemical redox cycling amplification strategy. In this system, ascorbic acid (AA), as the signal reporter for PEC and colorimetric assay, can be regenerated during the tris(2-carboxyethyl) phosphine-mediated chemical redox cycling process. For PEC detection, the reproduced electron donor AA could repeatedly combine with holes generated by the Bi2S3/Bi2O3 photoanode to effectively separate the photogenerated electron-hole. Besides, an AA-involved color reaction was evoked during the colorimetric assay to reduce colorless tris(bathophenanthroline) iron(III) to red tris(bathophenanthroline) iron(II). Owing to the ingenious signal amplification strategy, the developed dual-mode assay achieved the PEC and colorimetric determination of HSP90AA1 (one subtype of HSP family) in real samples. It is believed that this work will offer a new strategy to fabricate a dual-mode biosensor, which has great application prospects in the detection of various tumor biomarkers.

Advanced Dual-Mode Microfluidic Sensing Platform Based on Amphiphilic Polymer-Capped Perovskite Nanozymes Induced Photoelectrochemical Signal Amplification and Fluorescence Emission

A novel dual-mode microfluidic sensing platform integrating photoelectrochemical (PEC) and fluorescence (FL) sensors was developed for the sensitive monitoring of heart fatty acid binding protein (h-FABP). First, BiVO4/AgInS2 (BVAIS) composites with excellent photoelectric activity were synthesized as sensing matrices. The BVAIS heterojunction with a well-matched internal energy level structure provided a stable photocurrent. Second, an innovative signal amplification strategy based on octylamine-modified poly(acrylic acid) (OPA)-capped CsPbBr3 (OPCB) nanocrystals (NCs) with excellent catalytic activity and fluorescence property was proposed. On the OPCB nanozyme possessing ascorbate oxidase-like catalytic activity could catalyze the oxidation of ascorbic acid, which achieved quenching of the photocurrent signals by competitively consuming the electron donor. On the other hand, the OPCB NCs that overcame the water stability defect processed good luminescence performance and were able to produce obvious FL signals. Mutually verified dual-response signals effectively enhance the precision of test outcomes and avoid false-positive or false-negative results. Finally, the constructed microfluidic sensing platform realized sensitive detection of h-FABP in the linear range of 0.0001-150 ng/mL (PEC mode) and 0.001-150 ng/mL (FL mode), with detection limits of 36 fg/mL and 0.32 pg/mL, respectively. The present work provided a new perspective for designing an efficient dual-mode sensing strategy to achieve sensitive detection of disease markers.

Photoactive gate material-based organic photoelectrochemical transistor sensors: working principle and representative applications

Organic photoelectrochemical transistor (OPECT)-based sensors that use light-sensitive semiconductor materials as the gate have recently garnered increasing interest in various fields ranging from biological analysis to environmental monitoring. However, so far, the working principle and representative applications of OPECT sensors have not been discussed and reviewed systematically. In this review, we aim to present a comprehensive overview of the working principle and sensing mechanisms of OPECT-based sensors and various inorganic and organic photoactive gate materials used in OPECTs, with a focus on the representative applications and recent progress of these sensors in the fields of enzyme sensing, immunoassays, and nucleic acid-based sensing. Moreover, the challenges and outlooks that need to be addressed for future advancements in this field are summarized and discussed. This review will assist researchers in gaining a more comprehensive understanding and cognition of new OPECT-based sensing methods and devices.

Near-infrared-driven dual-photoelectrode photoelectrochemical sensing for fumonisin B1: Integrating a photon up-conversion bio-photocathode with an enhanced light-capturing photoanode

Fumonisin B1 (FB1), the most prevalent and highly toxic mycotoxin within the fumonisins family, poses threats to humans, especially in children and infants, even at trace levels. Therefore, it is essential to design an easy and sensitive detection strategy. Herein, a brand-new dual-photoelectrode photoelectrochemical (PEC) sensing platform for FB1 detection under near-infrared irradiation was unveiled. This platform integrated a photon up-conversion bio-photocathode substrate (UCNPs/Au/CuInS2, UCNPs: NaYF4: Yb3+, Er3+, Nd3+) and used a SnO2/SnS2@Bi/Bi2S3 heterojunction photoanode to greatly enhance light capture. Additionally, ZnO coated with polydopamine (ZnO@PDA) was utilized as a signal inhibitor. The restoration of photocurrent occurred due to the strong binding affinity between FB1 and its aptamer (FB1-Apt), facilitating the dissociation of FB1-Apt/ZnO@PDA from the photoelectrode. The PEC sensing performance and the electron transfer process were thoroughly examined. The developed "signal-restoration" PEC aptasensor exhibited a wider dynamic linear range from 1.0 × 10-3 to 1.0 × 102 ng/mL, with a lower limit of detection (0.13 pg/mL). It has demonstrated excellent practical detection performance in unspiked real samples, such as corn paste, with the FB1 enzyme-linked immunosorbent assay (ELISA) Kit serving as a reference, indicating its potential for routine analysis of other mycotoxins. Thus, this research establishes a feasible dual-photoelectrode PEC framework for the effective detection of mycotoxins and other hazardous substances.

Portable self-powered electrochemical aptasensor for ultrasensitive and real-time detection of microcystin-RR based on hydrovoltaic-photothermal coupling effect

Coupling different energy harvesting technologies to obtain an excellent output signal is essential for the development of high-performance self-powered electrochemical sensors. Herein, a novel hydrovoltaic-photothermal coupling self-powered electrochemical aptasensing platform was designed for sensitive detection of microcystin (MC-RR) with a digital multimeter as a direct visual readout strategy. The straightforward ultrasonic method was employed to synthesize polyaniline (PANI) and bismuth oxybromide (BiOBr) nanosheets, which were then integrated as active components in a hydrovoltaic device. The unique layer structure of two-dimensional (2D) nanomaterials BiOBr can create flexible interlayer spaces to accommodate various ions and water molecules, which was beneficial to construct evaporation-driven channels. Meanwhile, the exceptional photothermal characteristics of polyaniline could accelerate the water evaporation rate, consequently boosting the migration speed of charge carriers and increasing output signal. Moreover, a digital multimeter was connected to the constructed sensor for real-time displaying the output signal. With the assistance of aptamer, a novel self-powered electrochemical aptasensing platform was constructed for sensitive detection of MC-RR. Under optimum conditions, the output signal of the hydrovoltaic-photothermal coupling cell was linearly related to the logarithm of MC-RR concentration in the range of 1 fM to 1 nM with a detection limit of 0.31 fM (S/N = 3). Furthermore, this sensor also exhibited many advantages such as high selectivity, good repeatability and portability. Such novel strategy not only offers a completely new general approach to construct high-performance self-powered devices for the detection of MC-RR, but also provides a new strategy for advancing the miniaturization and field application of self-powered electrochemical sensors.

Self-powered multifunctional platform based on dual-photoelectrode for dual-mode detection and inactivation of Salmonella enteritidis

Self-powered photoelectrochemical (PEC) sensing is a novel sensing modality. The introduction of dual-mode sensing and photoelectrocatalysis in a self-powered system enables both detection and sterilization purposes. To this end, herein, a self-powered multifunctional platform for the photoelectrochemical-fluorescence (PEC-FL) detection and in-situ inactivation of Salmonella enteritidis (SE) was constructed. The platform utilized Bi4NbO8Cl/V2CTx/FTO as a photoanode and CuInS2/FTO as a photocathode and incubated quantum dot (QDs) signaling probes on the surface of the photocathode. During detection, the system drives the transfer of photogenerated electrons between the dual photoelectrodes through the Fermi energy level difference. The photoanode amplifies the photoelectric signal, while the photocathode is solely dedicated to the immune recognition process. QDs provide an additional fluorescence signal to the system. Under optimal experimental conditions, the multifunctional platform achieves detection limits of 3.2 and 5.3 CFU/mL in PEC and FL modes respectively, with a detection range of 2.91 × 102 to 2.91 × 108 CFU/mL. With the application of an external bias voltage, it further promotes electron transfer between the dual photoelectrodes, inhibits the recombination of photogenerated electrons and holes. It generates a significant amount of superoxide radicals (·O2-) in the cathodic region, resulting in strong sterilization efficiency (99%). The constructed self-powered multifunctional platform exhibits high sensitivity and sterilization efficiency, it provides a feasible and effective strategy to enhance the comprehensive capability of self-powered sensors.

Red and near-infrared light-activated photoelectrochemical nanobiosensors for biomedical target detection

Photoelectrochemical (PEC) nanobiosensors integrate molecular (bio)recognition elements with semiconductor/plasmonic photoactive nanomaterials to produce measurable signals after light-induced reactions. Recent advancements in PEC nanobiosensors, using light-matter interactions, have significantly improved sensitivity, specificity, and signal-to-noise ratio in detecting (bio)analytes. Tunable nanomaterials activated by a wide spectral radiation window coupled to electrochemical transduction platforms have further improved detection by stabilizing and amplifying electrical signals. This work reviews PEC biosensors based on nanomaterials like metal oxides, carbon nitrides, quantum dots, and transition metal chalcogenides (TMCs), showing their superior optoelectronic properties and analytical performance for the detection of clinically relevant biomarkers. Furthermore, it highlights the innovative role of red light and NIR-activated PEC nanobiosensors in enhancing charge transfer processes, protecting them from biomolecule photodamage in vitro and in vivo applications. Overall, advances in PEC detection systems have the potential to revolutionize rapid and accurate measurements in clinical diagnostic applications. Their integration into miniaturized devices also supports the development of portable, easy-to-use diagnostic tools, facilitating point-of-care (POC) testing solutions and real-time monitoring.

Dual Engine Boosts Organic Photoelectrochemical Transistor for Enhanced Modulation and Bioanalysis

Organic photoelectrochemical transistor (OPECT) has shown substantial potential in the development of next-generation bioanalysis yet is limited by the either-or situation between the photoelectrode types and the channel types. Inspired by the dual-photoelectrode systems, we propose a new architecture of dual-engine OPECT for enhanced signal modulation and its biosensing application. Exemplified by incorporating the CdS/Bi2S3 photoanode and Cu2O photocathode within the gate-source circuit of Ag/AgCl-gated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) channel, the device shows enhanced modulation capability and larger transconductance (gm) against the single-photoelectrode ones. Moreover, the light irritation upon the device effectively shifts the peak value of gm to zero gate voltage without degradation and generates larger current steps that are advantageous for the sensitive bioanalysis. Based on the as-developed dual-photoelectrode OPECT, target-mediated recycling and etching reactions are designed upon the CdS/Bi2S3, which could result in dual signal amplification and realize the sensitive microRNA-155 biodetection with a linear range from 1 fM to 100 pM and a lower detection limit of 0.12 fM.