Development of a Layered Electrochemical Biosensor

Robert Kellerman

Content Creator

09 April 2026

This research focuses on addressing the urgent need for faster, more accessible tuberculosis (TB) screening in South Africa. Dr Stephan Schoeman developed a portable, low-cost electrochemical biosensor designed to detect TB-related biomarkers quickly at the point of care, reducing reliance on complex laboratory infrastructure.
Through iterative prototyping, the team engineered a compact, disposable device using carbon nanofibre electrodes and a layered design with built-in test validation. The final sensor (Sensor M) demonstrated high sensitivity across clinically relevant ranges by detecting C-reactive protein (CRP), delivering reliable results within minutes.
The biosensor’s affordability, ease of use, and adaptability make it a promising tool for use in resource-limited settings such as mobile clinics. Beyond TB, the platform has potential applications in diagnosing other diseases, supporting broader public health efforts.
Next steps include clinical validation, scaling up manufacturing, and expanding the device to detect multiple biomarkers simultaneously, further improving diagnostic accuracy and impact.

Tuberculosis (TB) remains one of South Africa’s toughest public health problems. Dr Stephan Schoeman, under the supervision of Professors Willie Perold and Gerhard Walzl, designed, built, and tested a portable electrochemical biosensor that promises quicker, easier screening, especially where laboratory resources are scarce.

Why Faster TB Screening Matters

The World Health Organisation estimates that 10.6 million people developed TB in 2021, with 8.2 million new people diagnosed in 2023. South Africa recorded one of the highest incidence rates worldwide. Yet hundreds of thousands of cases still go undetected each year. Current clinic-based tests rely on sputum samples, expensive instruments, and skilled technicians—conditions that are difficult to guarantee in many primary-care settings.

To close that gap, the WHO has issued target product profiles calling for low-cost devices that can detect TB from markers in blood, urine, or breath. That challenge inspired Dr Schoeman’s research: the design of a miniaturised, disposable biosensor able to quantify TB-linked proteins at the point of care.

The Research Objectives

In light of the above, the research team set five objectives:

Review the landscape: Map existing TB biosensors and electrochemical detection techniques.
Analyse a commercial sensor: Benchmark sensitivity, stability, and ease of manufacture.
Prototype iteratively: Test materials, electrode layouts, and bonding methods across multiple design cycles.
Prove the concept: Use the final build to measure a clinically relevant biomarker, C-reactive protein (CRP).
Chart the road ahead: Outline improvements and broader applications.

Building the Device—One Prototype at a Time

Early designs borrowed ideas from glucose test strips and lateral-flow assays. Carbon nanofibres were selected as the electrode material for their high surface area and biocompatibility. A porous membrane was sandwiched between two working electrodes, creating a control channel that validates every test, much like the control line on a home pregnancy test.

Six successive prototypes tackled manufacturability hurdles such as reliable micro-patterning, fluid routing, and encapsulation. The final version, dubbed Sensor M, integrated all lessons learned:

Four-electrode cell: Two working electrodes (test + control), one reference, one counter.
Plug-and-play reagent layer: Pre-coated with capture antibodies specific to CRP.
Disposable cartridge: Fabricated entirely with equipment available in the Department of Electrical and Electronic Engineering.

Sensor M detected CRP across an impressive 10 ng/mL – 1 pg/mL range—a thousand-fold span that covers concentrations relevant to TB triage. The built-in control electrode confirmed assay validity in every run, boosting confidence in field conditions where repeat testing is costly.