A fully inkjet-printed disposable glucose sensor on paper

Inexpensive and easy-to-use diagnostic tools for fast health screening are imperative,especially in the developing world,where portability and affordability are a necessity.Accurate monitoring of metabolite levels can provide useful information regarding key metabolic activities of the body and detect the concomitant irregularities such as in the case of diabetes,a worldwide chronic disease.Today,the majority of daily glucose monitoring tools rely on piercing the skin to draw blood.The pain and discomfort associated with finger pricking have created a global need to develop non-invasive,portable glucose assays.In this work,we develop a disposable analytical device which can measure physiologically relevant glucose concentrations in human saliva based on enzymatic electrochemical detection.We use inkjet-printing technology for the rapid and low-cost deposition of all the components of this glucose sensor,from the electronics to the biorecognition elements,on commercially available paper substrates.The only electronic component of the sensor is the conducting polymer poly(3,4 ethylenedioxythiophene)doped with polystyrene sulfonate(PEDOT:PSS),while the biorecognition element comprises of the enzyme glucose oxidase coupled with an electron mediator.We demonstrate that one month after its fabrication and storage in air-free environment,the sensor maintains its function with only minor performance loss.This fully printed,all-polymer biosensor with its ease of fabrication,accuracy,sensitivity and compatibility with easy-to-obtain biofluids such as saliva aids in the development of next generation low-cost,noninvasive,eco-friendly,and disposable diagnostic tools.

Self-healable stretchable printed electronic cryogels for in-vivo plant monitoring

A key challenge in bioelectronics is to establish and improve the interface between electronic devices and living tissues,enabling a direct assessment of biological systems.Sensors integrated with plant tissue can provide valuable information about the plant itself as well as the surrounding environment,including air and soil quality.An obstacle in developing interfaces to plant tissue is mitigating the formation of fibrotic tissues,which can hinder continuous and accurate sensor operation over extended timeframes.Electronic systems that utilize suitable biocompatible materials alongside appropriate fabrication techniques to establish plantelectronic interfaces could provide for enhanced environmental understanding and ecosystem management capabilities.To meet these demands,this study introduces an approach for integrating printed electronic materials with biocompatible cryogels,resulting in stable implantable hydrogel-based bioelectronic devices capable of long-term operation within plant tissue.These inkjet-printed cryogels can be customized to provide various electronic functionalities,including electrodes and organic electrochemical transistors(OECTs),that exhibit high electrical conductivity for embedded conducting polymer traces(up to 350 S/cm),transconductance for OECTs in the mS range,a capacitance of up to 4.2mF g−1 in suitable structures,high stretchability(up to 330%strain),and selfhealing properties.The biocompatible functionalized cryogel-based electrodes and transistors were successfully implanted in plant tissue,and ionic activity in tomato plant stems was collected for over two months with minimal scar tissue formation,making these cryogel-based printed electronic devices excellent candidates for continuous,in-situ monitoring of plant and environmental status and health.