In industries such as aerospace, wearables, building materials and life sciences, two-dimensional ‘monolayer’ materials are gaining growing acceptance as advanced sensor substrates.
In particular, graphene is a single atomic layer carbon, and is thriving as the ideal sensing material for users. It is preferred over other 2D materials due to its performance, sustainability, manufacturability, availability, cost and how easy it is to use for a plethora of form factors.
A specific area of development for single-layer graphene is its usage in biosensing as a sensing platform. Numerous peer-reviewed papers are investigating the new and empowering abilities of this material in biotech. These areas are extremely diverse and range from wearable blood pressure monitors to advanced glucose sensors, and even the identification of small molecules for the discovery of new drugs.
Innovative developments have been made to allow for faster answers and improved data management for diagnosis and prescriptive cures. This is possible with a new graphene-based ‘crispr chip’ that is promoted as aiding in the ‘internet of biology’. DNA and other biological answers are now available immediately in a digital format.
The question many people want to know the answer to is, how are these innovative graphene-based biosensors made? Many of these devices are currently manufactured in the silicon wafer fabrication environment. This takes place in MEMS fabs or boutique wafer foundries where specialty computer chips are also produced.
Advanced biodevice manufacturers or designers that have ideas for a novel device first take the obvious step of going to these silicon wafer-based contractors. Everything required to manufacture at the nano-scale is available in these labs. This has resulted in nearly all of these devices being designed to exist on silicon wafers, typically because of the practical manufacturing restrictions of the day.
Do Graphene Sensors Have to be Manufactured on Silicon Chips?
It has been discovered that within most of these graphene biosensor devices, the underlying silicon plays no part in the functioning. The silicon is not involved in these graphene biosensors at all because all of the working ‘plumbing’ is situated on top of the wafer surface. Therefore, it acts purely as a ‘tray’ to support the processing stages that create the sensor and have nothing to do with its function.
For most of the graphene biosensing designs, the silicon allows the graphene device to reside on top during the patterning, etching and deposition processes that occur to make the device. An example where this isn’t the case is for classic semiconductor devices in which silicon plays an important semiconducting role in its function.
The majority of the current graphene biosensors are designed with greater geometries (several >10 um, in contrast to a number in the nanometer scale) compared to those usually used for semiconductor chips. This results in cheaper, easier and largely available processing techniques that do not involve the investment in large, exotic, and expensive equipment found in chip factories.
If the device is processed outside of the silicon environment, there is large savings in time and money.
The ability to skip the silicon process in the manufacturing of the sensor device opens many doors and allows ease of production, throughput and cost. For example, ‘shadow masking’ can be done with simple and largely available techniques for the patterning stage.
This enables the next important concept of being able to create these devices on different types of plastics as an alternative to silicon. As a result, high throughput schemas like ‘roll-to-roll’ and other manufacturing methods that have been used cheaply for decades can be utilized.
Form Factor and New Application Benefits are Possible on Plastic
When the graphene biosensor manufacturing process is taken out of the silicon wafer fab, it generates opportunities for throughput and cost benefits. Additionally, it allows a completely new packaging and application possibility that was not practical when devices were made on silicon.
For instance, ‘blister packs’ that are used for over the counter pills or throat lozenges at the drug store are now being utilized for graphene biosensors. The blister pack design protects the graphene sensor until it is used. It pre-charges the environment inside the blister pack with functionalizing chemistry which awaits the analyte chosen to be injected into the sensor environment. This is done by piercing the blister pack when it’s time for measurement.
This is an easy and cheap way for a farmer to transport graphene-based sensors in his pocket when they are out testing crop health in the field.
Biodegradable plastics can also be used. Graphene sensors such as these can be created for pennies with packing technologies that have been used for a long time. This new way of thinking about graphene biosensors on plastic instead of on silicon applies to many graphene sensing modalities such as strain sensors, gas sensors, graphene FET’s, and many others.
Who Supplies Graphene Sensors on Plastic?
In San Diego, California, US, Grolltex (for ‘graphene-rolling-technologies’) is one of the new suppliers of materials and production foundries manufacturing graphene sensors on plastic.
Grolltex is the principal producer of electronics grade graphene material for biosensing in North America. It has many significant patents in the design and production of multi-modal graphene sensors and the methods to produce them in high throughput, inexpensive schemas.
They are currently transporting prototypes of advanced graphene sensors on plastic that dramatically decreases the cost of manufacturing by over 100x in some cases, in addition to providing several new packaging options such as the blister pack mentioned above.
This information has been sourced, reviewed and adapted from materials provided by Grolltex Inc.
For more information on this source, please visit Grolltex Inc.