Graphene Solution-Gated Field-Effect Transistor for Ultrasound-Based Wireless and Battery Free Biosensing

The development of wireless and battery free sensors for biomedical applications is a fastgrowing research and industrial field. It promises to greatly improve the patient's comfortduring the diagnosis phase but also in the treatment of chronic diseases. While the standardtechnologies have been based for the last decade on electromagnetic waves, ultrasonic poweringand communication is offer promising perspective to further reduce the size of the sensor inorder to develop minimally invasive implantable technology. Wireless and battery-freeultrasound-based devices for healthcare monitoring usually comprise a piezoelectric elementfor the powering and communication and a variable shunt load that varies according to thephysiological parameter of interest. The changes in the shunt load modifies the acousticreflectivity of the piezoelectric element, which can be detected using a pulse-echo protocol. Inthe present study, we introduce the use of graphene solution-gated field effect transistors, awell-established biotransducer, as a new type of shunt load. Using a mm-sized graphenesolution-gated field-effect transistor, we show that the amplitude of an ultrasonic wave thatreflects on the piezoelectric component, can be modulated by the gate voltage of the transistor.We thus established the transfer curve of Echo Vs Gate voltage in physiological medium andthrough a biological tissue. This study sets the basis toward a new type of ultrasound-basedwireless and battery-free biosensors.