Technology

Changing the Paradigm for Air and Waterborne Pathogen Detection

Continuous, real-time pathogen detection and identification with reliable results.

Novel pathogen detection technology in development by BiSen Tech is fundamentally different from all existing technologies. The patented technology behind this system allows for continuous and remote monitoring for the presence of targeted pathogens and for rapid pathogen detection and identification.

FEATURES

HOW IT WORKS

Pathogen detection within seconds.
Pathogen identification and quantification within minutes.
Unprecedented single-cell or single-virus sensitivity.
Flexible design allows for detection of multiple types of protozoa, bacteria, and viruses.
Low operating cost with no consumables, laboratory equipment, or personnel required.
Small form factor can be used in fixed installations or in portable devices as small as a cell phone.

BiSen Tech’s sensors integrate microbiology and chemistry with semiconductor device physics.

Our multi-disciplinary approach joins together:

A uniquely designed Field Effect Transistor (FET)—a type of transistor, or semiconductor device, used in everyday electronic devices.
Biomolecular probe technology that leverages relative permittivity, a known physical property of microbes, to cause the transistor to turn on for a set period and allow for the detection and identification of a targeted pathogen.

No other existing technology utilizes the relative permittivity of pathogens to detect their presence.

Details

A standard FET is built in a layered fashion like a layered cake—the gate electrode lays flat upon the oxide gate insulator which in turn lays flat upon the semiconductor material (Fig. 1). When voltage is applied to the gate electrode, an electric field arises between the gate electrode and the semiconductor. If the voltage exceeds the threshold voltage—the minimum voltage required to create a path of conduction between the source and the drain terminals—the transistor turns on; otherwise, it remains off.

With BiSen Tech’s unique transistor, the gate electrode is constructed at a right angle to the plane of the device and is slightly offset from the oxide insulator and semiconductor (Fig. 2 and Fig. 3)—we refer to this as an Orthogonal (offset) Gate Field Effect Transistor (OGFET). When voltage is applied to the orthogonal gate electrode of an OGFET, an electric field still arises between it and the semiconductor and it functions in the same way as a standard FET—if the voltage is higher than the threshold voltage, the transistor turns on; otherwise, it remains off.

Figure 1: Standard Field Effect Transistor (FET)

Figure 2: BiSen Tech’s Orthogonal Gate Field Effect Transistor (OGFET)

Figure 3: Top-Down View of BiSen Tech’s Orthogonal Gate Field Effect Transistor (OGFET)

Figure 4: Plot of Log Relative Permittivity Versus Log Measurement Frequency for E. Coli and Other Substances

BiSen Tech’s biosensors employ a unique method to increase the sensitivity of the individual detector elements, allowing the target pathogen to act as an electrical field shunt to turn the transistor on - even if the pathogen is not fully occupying the interior angle of the OGFET.

The Difference

The difference with BiSen Tech’s transistor is that it can also turn on when the voltage applied is less than the typically required threshold voltage if a microbe is present. This is because microbes have a high relative permittivity—the ability to transfer an electric field—as compared to that of empty space.

Relative permittivity as a function of measurement frequency is a well-known physical property of microbes. For example, the relative permittivity of Escherichia coli (E. coli) at 10 Hz is 800,000, while that of water is about 80 (Fig. 4). As a result, if a water sample is being tested for the presence of harmful microbes but none are present, BiSen Tech’s OGFET will not turn on if the interrogation voltage applied is less than the threshold voltage (Fig. 5).

However, if, at that same voltage, even a single microbe is present and even just partially occupying the interior angle of the OGFET between the orthogonal gate and the semiconductor, the microbe's high relative permittivity will transfer an electrical field so that it is strong enough to allow the transistor to turn on even though the threshold voltage has not been reached (Fig. 6).

Figure 5: Standard Field Effect Transistor (FET)

Figure 6: Standard Field Effect Transistor (FET)

BiSen Technology Fundamentals

Microbe Identification

As explained above, the presence of a microbe at an OGFET permits the transistor to turn on. If BiSen Tech’s transistor signals the presence of a microbe by turning on when the applied interrogation voltage is lower than the necessary threshold voltage (Fig. 6), the next step is to determine what type of microbe is present. Microbe identification is accomplished through the use of molecular probe technology. Molecular probes are strands of specific antibodies or other types of aptamers (synthetic antibodies) that are designed to capture specific targeted pathogens, such as particular strains of E. coli, and to ignore "non-target" pathogens. Using a BiSen Tech proprietary coating, the interior angle of the OGFET is functionalized by tightly bonding the molecular probes to the gate insulator.

Catch-and-Release Process

When functionalized OGFET is exposed to non-target pathogens, the non-target pathogen is not immobilized. But when a target pathogen is presented to Bisen Tech’s OGFET, the molecular probes specific to that pathogen will immobilize the pathogen at the transistor and hold onto it for a specified period of time, allowing for real-time pathogen detection and identification with no time-consuming target preparation or amplification required. Once the immobilization time ends, the molecular probes release the pathogen and the transistor becomes available for continued target pathogen detection and will continue to catch and release targeted pathogens, if more are present. Successive interrogations of the transistor indicate the continuous presence of the target pathogen. This continued catch-and-release process, made possible by the OGFET’s self-cleaning sensor elements, enables the calculation of pathogen concentration levels. If a “non-target” microbe is presented to the OGFET, it will not be immobilized and held by the molecular probes and successive interrogations of the OGFET will show no pathogen is present.

Sensor Elements

BiSen Tech’s biosensor will have several hundred thousand individual sensor elements designed for detecting protozoa, up to a million sensor elements for bacteria, and several million or more sensor elements for viruses, with each sensor element capable of interrogation every 1 to 2 seconds. With the large number of sensor elements on the BiSen chip, the array can be segmented, which each segment coated with a different molecular probe, allowing a single chip to detect multiple targeted air- or waterborne target pathogens.

BiSen Tech’s paradigm-shifting technology is patent protected.

Why BiSen Tech

Advantages of BiSen's Pathogen Detection Technology

Compared with existing pathogen detection systems, BiSen Tech’s patented technology offers multiple advantages:

Contact us to inquire about partner or license opportunities.

BiSen is ready to make our paradigm-shifting pathogen detection and identification system a reality. Join us!