Nanosensor : Components, Types, Working, Fabrication Techniques, Types & Its Applications

The first nanosensor example was developed in 1999 at the Georgia Institute of Technology by researchers an innovation created from carbon nanotubes. A nanosensor is a unique kind of sensor and they are small platforms that are designed for detecting and measuring chemical, biological, physical, or environmental information at the nanoscale level. These sensors are ideal mainly for sensing applications because of their unique nanoparticle properties like; their huge surface region to level ratio. This article provides brief information on nanosensors, their working, types, and their applications.

Nanosensor Definition

A type of sensor with a few nanometer’s characteristic dimensions is known as a nanosensor. This is a mechanical or chemical sensor, used to detect the occurrence of nanoparticles, and chemical species or check different physical parameters. These are used in medical diagnostic applications like sensing water quality, food & other chemicals. This sensor works similarly to a normal sensor but it detects small quantities & changes them into signals that should be analyzed. Nanosensors are used in transportation systems, pathogen detection, medicine, manufacturing, pollution control, etc.

Some of the nanosensor examples are; fluorescent nanosensors made with DNA or peptides, carbon nanotubes, quantum dots, nanosensors depending on plasmon coupling, magnetic resonance imaging, and photoacoustic.

Nanosensor Components

The nanosensor components mainly include an analyte, sensor, transducer & a detector. Nanosensors are capable of measuring the single-molecule point level. Generally, these sensors function by following the electrical changes within the sensor materials.

In this diagram, first, the analyte from the solution diffuses to the surface of the nanosensor. After that, it responds specifically & efficiently, so this changes the transducer surface physicochemical properties, which leads to a change within the electronic (or) optical properties of the face of the transducer. Finally, this is changed into an electrical signal which is detected

Nanosensor Working Principle

Nanosensor works by tracking the electrical changes within the sensor materials. The fundamental parts of a nanosensor are; the analyte, transducer, detector & the feedback line from the detector toward the sensor block. Nanosensor measures single molecule levels & work by simply maintaining an electrical change within the sensor material.

The analyte in this sensor diffuses first from the solution to the surface of the sensor & responds exactly and very effectively by changing the physicochemical properties of the surface. After that, it causes a change in the electronic optical transducer properties. So finally this change can be converted into an electrical signal that is noticed.

Nanosensor History

• Nanosensor as “Nanoprobe” was founded in the year 1990 and built on research at IBM Sindelfingen conducted on required basic technologies for the silicon AFM probes batch processing with bulk micromachining.
• Nanosensors commercialized AFM & SPM probes globally in the year 1993. So their developments within batch processing technologies for creating AFM probes contributed to initiating Atomic Force Microscopes into the time industry.
• In the identification of this realization, these sensors discerned the Award of Dr.-Rudolf-Eberle Innovation for the German State of Baden-Württemberg, the German Industry Innovation Prize in the year 1995 and the Förderkreis für die Mikroelektronik e.V Innovation Award in the year 1999. Nanosensors in 2002 was obtained & integrated into Switzerland-based NanoWorld which is an independent business unit.
• In 2003, these sensors introduced an innovative new AFM-type probe like AdvancedTEC™. It allows exact positioning & makes this probe provide Real Tip Visibility throughout an atomic force microscope optical system even whenever the AFM probe is tilted slightly because of its mounting.
• Sensors in 2003 appointed NanoAndMore GmbH as its new official distributor for Turkey, Israel & Europe.
• In 2004, the PointProbe® Plus was introduced which unites the familiar proven PointProbe® Series features like compatibility & high application versatility with commercial AFMs.
• In 2005, the Q30K-Plus was announced which is a a novel AFM probe scanning proximity with an excellent Q-factor & an enhanced S/N ratio for UHV applications.
• Nanosensors 2006 changed the North American distribution network, a member of NanoWorld Group,
• NanoAndMore USA Corp., became the Nanosensor’s official distributor within the USA, Mexico & Canada.
• Nanosensors 2007 launched a new silicon MFM AFM probe series, introduced the PointProbe® Plus XY-Alignment series, launched the Plateau Tip AFM probes series, and announced the PointProbe® Plus AFM probe Series.
• In 2008, it introduced the self-actuating & self-sensing Akiyama probe.
• Nanosensor 2011 uploaded its initial special development list and announced a new wear-resistant, conductive AFM probe series, and the Platinum Silicide AFM probes.
• In 2013, it is announced the primary two screencasts on its YouTube channel.
• It introduced a new AFM probes series known as the uniqprobe™ in 2013.

Nanosensor Fabrication Techniques

There are several techniques proposed to make these sensors like; top-down lithography, bottom-up assembly & molecular self-assembly.

1. Top-Down Approaches
   • Lithography: This method involves etching nanoscale patterns onto substrates using techniques like electron beam lithography (EBL) or photolithography. EBL, in particular, offers high resolution, allowing for precise patterning essential for creating nanoscale features.
   • Etching: Both wet and dry etching methods are used to remove material selectively from the surface of a substrate to create nanoscale structures. Reactive ion etching (RIE) is a popular dry etching technique for its precision and ability to create complex patterns.
2. Bottom-Up Approaches
   • Chemical Vapor Deposition (CVD): CVD is a process where gaseous reactants form solid materials on substrates, creating thin films and nanostructures. Variants like plasma-enhanced CVD (PECVD) enhance the process by using plasma to increase reaction rates.
   • Self-Assembly: This technique involves the spontaneous organization of molecules into structured arrangements. DNA nanotechnology, for instance, utilizes the base-pairing properties of DNA to create intricate nanostructures.
   • Sol-Gel Processing: This involves the transition of a solution system from a liquid ‘sol’ into a solid ‘gel’ phase. It’s particularly useful for creating ceramic and glassy nanostructures.
3. Hybrid Approaches

                      Nanoimprint Lithography (NIL): This combines aspects of both top-down and bottom-up approaches. It involves pressing a nanostructured mold into a polymer layer, then curing the polymer to transfer the nanoscale features.

Types of Nanosensors

There are different types of nanosensors which are discussed below.

Physical Nanosensors

These sensors are used for measuring changes within physical quantities like velocity, temperature, pressure, electric forces, displacement, mass, and many more. These nanosensors are used in various applications in daily life & also in industries. Nanowear Inc. utilizes physical nanosensors for making wearable undergarments to find a possible heart failure before it occurs in chronically ill patients by looking at changes within the electric signals from our bodies.

Chemical Nanosensors

These sensors help in detecting different chemicals (or) chemical properties like pH value. So this is useful whenever looking at ecological pollution (or) for pharmaceutical analysis. Usually, these sensors are fabricated from different nanomaterials like metal nanoparticles or graphene because these respond to the occurrence of particular target chemicals that need to be calculated.

The best example of this sensor is to detect a liquid’s pH value. An investigated group was able to build such a type of sensor using polymer brushes covered with gold nanoparticles to detect the pH value with spectroscopic technique.

Nano-biosensors

Nano biosensors in medicine & healthcare can exactly detect pathogens, toxins, tumors & biomarkers. These sensors convert the response of molecules into optical or electrical signals and have the benefit of being able to aim extremely specifically at what is required to be measured. Whenever an object’s size and its surface-to-volume ratio turn bigger, then these sensors have a big benefit to bigger biosensors to provide better sensing when the reaction through the targeted molecules occurs more frequently.

These sensors are used by Taiwanese start-up Instant NanoBiosensors Co., Ltd. They utilize an optical fiber covered with gold nanoparticles & antibodies for detecting various biological compounds.

Optical Nanosensor

Optical nanosensors have nanoscale (or) nanostructured sensor materials that demonstrate a different reaction at optical frequencies to electromagnetic excitation. These sensors are mainly used for analytical reasons for monitoring as well as identifying chemical or biological processes. These sensors also change the data into signals for important information.

Advantages and Disadvantages

The advantages of nanosensors include the following.

• Nanosensors can easily interact at the nano level & they observe unique developments at the nano level which are different from the macro level.
• These sensors have high sensitivity that allows more accuracy.
• These are durable, stable, portable, high sensitivity, small, robust response, real-time detection, selectivity, and lightweight,
• This sensor has low power consumption
• It requires a low sample volume for analyzing & causing the least disturbance to the observed material.
• This sensor’s response time is low and has more speed than other sensors, which lets them perform real-time analysis.
• This sensor detects various things simultaneously which allows for a variety of functions.
• Nanosensors display significant ranges of detection sensitivity (or) resolution.
• These sensors operate on a smaller scale.
• They have greater sensitivity & more accuracy.

The disadvantages of nanosensors include the following.

• These sensors are normally less selective mainly for biological measurements because they lack the higher specificity for bio-receptors like DNA, and antibodies.
• The top-down fabricated nanosensor has limited resolution & they are expensive.
• The bottom-up type nanosensors are very low efficient, have large scaling & are extremely expensive as compared to others.

Applications

The applications of nanosensors include the following.

• Nanosensors are used mainly for a large number of applications within plant sciences such as; steady energy supply, detecting metabolic activities, storing, and computing information, and also to detect & responding to a broad range of ecological stimuli.
• This is a unique type of sensor, designed mainly to detect & measure chemical, biological, environmental (or) physical information at the nanoscale level.
• These are mechanical or chemical sensors, used in different applications which range from biomedical industries to environmental industries.
• Some common applications of these sensors mainly include;
• These sensors help in detecting a variety of chemicals within gases for monitoring pollution.
• A nanosensor is used to monitor physical parameters like displacement, flow & temperature.
• Nanosensors help in monitoring plant signaling & metabolism to understand plant biology.
• It helps in studying neurotransmitters within the brain to recognize neurophysiology.
• These sensors can be used as accelerometers within MEMS devices like airbag sensors.
• It is used to gather real-time soil condition measurements like; pH, nutrients, moisture & residual pesticides mainly for agricultural purposes.
• This sensor is used for detecting pesticides on vegetables & fruits to detect carcinogens within food.
• It detects pathogens within food as an element of food security & quality control measures.
• This sensor detects & monitors small-molecule metabolites.
• It is used for real-time metabolic cancer cell activity monitoring in response to therapeutic intrusion.

Thus, this is an overview of a nanosensor, their working, types, advantages, disadvantages, and applications. A nanosensor is a nanoscale device that measures physical quantities & also changes into signals that can be detected as well as analyzed. These sensors are available in different types used in various applications like defense, healthcare & environmental industries. There are different techniques available to fabricate these types of sensors; top-down lithography, second is bottom-up assembly and third is molecular self-assembly. Here is a question for you, nanosensor is invented by?