Achieving high sensitivity and minimising signal noise at the same time is a core challenge in biosensor development, particularly in electrochemical examples where weak biological signals are transduced into measurable electrical outputs. Without the proper precautions, noise can impact sensitivity and lead to issues like false negatives and positives.
Even state-of-the-art devices can face limitations imposed by noise, both intrinsic and environmental. Engineers need to know the root causes of noise in biosensors to then be able to apply the advanced material-based and system-level strategies to mitigate them.
In biosensors, noise fundamentally impairs the sensor’s ability to extract accurate and clinically meaningful data. This has several implications across key performance metrics.
Noise in biosensors can be broadly categorised into electronic noise, environmental interference and biological cross-reactivity. Each poses unique obstacles to precision, especially in real-time and point-of-care diagnostics.
This is a form of electronic noise that arises from the random motion of charge carriers within the conductive components of the sensor. Thermal noise is proportional to temperature and resistance and is present in all conductive materials. It becomes particularly problematic when dealing with ultra-low signal levels, such as in femtomolar detection.
Prevalent at low frequencies, this noise is introduced by imperfections in electrode materials and interfaces. In nanostructured transducers, flicker noise can be amplified due to increased surface area and defects, particularly at grain boundaries or at heterogeneous junctions.
This includes noise from external sources such as power lines and wireless communication devices. It often couples capacitively or inductively into the sensor system that leads to fluctuations in baseline measurements.
Addressing noise requires a multi-layered approach combining materials engineering, surface chemistry and smart system design. The following strategies outline how biosensor developers can suppress interference and maximise signal fidelity across a range of operating conditions with the use of innovative new materials.
Electrode material plays a pivotal role in determining both noise levels and sensitivity. Traditionally used materials such as gold or platinum offer excellent conductivity but are susceptible to biofouling and are costly. Recent advances focus on carbon-based nanostructures for their unique electronic and mechanical properties.
Antifouling layers based on nanocomposites (e.g., BSA/prGOx/GA) or polyethylene glycol chains can dramatically reduce non-specific adsorption. These coatings suppress biochemical noise from complex matrices like blood or saliva and maintain the integrity of the sensor's signal response. However, these coatings can also reduce sensor signal by slowing down access of the target analyte on the transducer surface and acting as a barrier that limits electron transfer.
New carbon nanomaterials exhibit innate antifouling properties which is particularly important for use in complex biological matrices such as blood, saliva or serum. These exciting materials help improve accuracy and reproducibility in sensing performance without the need for additional antifouling coatings or surface treatments. At the same time, these materials provide greater signal response as they do not run into the same sensor signal issues as coatings.
These nanomaterials also showcase high surface-to-volume ratios, improved electron mobility and tunable surface chemistry. These properties enable reduced thermal and flicker noise due to higher conductivity and fewer grain boundaries. On top of this, they increase sensitivity through enhanced surface area for biorecognition element immobilisation.
Reducing noise and enhancing sensitivity is a key component of biosensor development, particularly for electrochemical platforms where weak signals can be easily masked. Material selection, interface design and surface chemistry all play a critical role in suppressing noise to improve performance in real-world applications.
Gii is a new carbon nanomaterial designed specifically to address these challenges. It combines high conductivity with a large active surface area, is inherently anti-fouling and enables stability without degrading signal quality. Crucially, it delivers the same or better performance of noble metals and graphene with greater reproducibility, scalability and sustainability.
To learn more about how Gii works and how it can be integrated into your biosensing platform, explore our technical guide below.