Sweat analysis with a wearable sensing platform based on laser-induced graphene

The scientific community has shown increasing interest in laser scribing for the direct fabrication of conductive graphene-based tracks on different substrates. This can enable novel routes for the noninvasive analysis of biofluids (such as sweat or other noninvasive matrices), whose results can provide the rapid evaluation of a person's health status. Here, we present a wearable sensing platform based on laser induced graphene (LIG) porous electrodes scribed on a flexible polyimide sheet, which samples sweat through a paper sampler. The device is fully laser manufactured and features a two layer design with LIG-based vertical interconnect accesses. A detailed characterization of the LIG electrodes including pore size, surface groups, surface area in comparison to electroactive surface area, and the reduction behavior of different LIG types was performed. The bare LIG electrodes can detect the electrochemical oxidation of both uric acid and tyrosine. Further modification of the surface of the LIG working electrode with an indoaniline derivative [4-((4-aminophenyl)imino)-2,6-dimethoxycyclohexa-2,5-dien-1-one] enables the voltammetric measurement of pH with an almost ideal sensitivity and without interference from other analytes. Finally, electrochemical impedance spectroscopy was used to measure the concentrations of ions through the analysis of the sweat impedance. The device was successfully tested in a real case scenario, worn on the skin during a sports session. In vitro tests proved the non-cytotoxic effect of the device on the A549 cell line

Development of Solution Blow Spun Nanofibers as Electrical and Whole Cell Biosensing Interfaces

Infectious pathogens place a huge burden on the US economy with more than $120 billion spent annually for direct and indirect costs for the treatment of infectious diseases. Rapid detection schemes continue to evolve in order to meet the demand of early diagnosis. In chronic wound infections, bacterial load is capable of impeding the healing process. Additionally, bacterial virulence production works coherently with bacterial load to produce toxins and molecules that prolongs the healing cycle. This work examines the use of nonwoven polymeric conductive and non-conductive nanofiber mats as synthetic biosensor scaffolds, drug delivery and biosensor interface constructs. A custom-made nanofiber platform was built to produce solution blow spun nanofibers of various polymer loading. Antimicrobial nanofiber mats were made with the use of an in-situ silver chemical reduction method. Ceria nanoparticles were incorporated to provide an additional antioxidative property. Conductivity properties were examined by using silver and multi-walled carbon nanotubes (MWCNT) as a filler material. SBS parameters were adjusted to analyze electrical conductivity properties. Nanofiber mats were used to detect bacteria concentrations in vitro. Protein adhesion to conductive nanofibers was studied using fluorescent antibodies and BCA assay. Anti-rabbit and streptavidin Alexa Flour 594 was used to examine the adsorption properties of SBS nanofiber mats. Enhancements were made to further improve interface design for specificity. SBS nanofiber electrodes were fabricated to serve as scaffold and detection site for spike protein detection. Bacteria virulence production was examined by the detection of pyocyanin and quorum sensing molecules. The opportunistic pathogen, Pseudomonas aeruginosa is a nosocomial iii pathogen found in immunocompromised patients with such as those with chronic wounds and cystic fibrosis. Pyocyanin is one of four quorum sensing molecules that the pathogen produces which can be detected electrochemically due to its inherent redox-active activity. SBS has been used to develop a sensing scheme to detect pyocyanin. This work also examines the use of a synthetic biosensor with a LasR based system capable of detecting homoserine lactone produced by P. aeruginosa and other common gram-negative pathogens. Genetic modifications were made to biosensor in order to replace a green, fluorescent reporter with a chromoprotein based reporter system for visual readout. Additionally, work related to community service and outreach regarding the encouragement of middle school students to pursue Science, Technology, Engineering and Math (STEM) was conducted. Results from outreach program showed an increase in the STEM interest among a group of middle school students. There was a general trend with STEM career knowledge, STEM self-efficacy and the level of interest in STEM careers and activities. Military research was also done with the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) to develop several assays for the detection of several highly infectious viruses and bacteria. Due to confidentiality, the work cannot be published in this manuscript

Micromachined three-dimensional electrode arrays for in-vitro and in-vivo electrogenic cellular networks

This dissertation presents an investigation of micromachined three-dimensional microelectrode arrays (3-D MEAs) targeted toward in-vitro and in-vivo biomedical applications. Current 3-D MEAs are predominantly silicon-based, fabricated in a planar fashion, and are assembled to achieve a true 3-D form: a technique that cannot be extended to micro-manufacturing. The integrated 3-D MEAs developed in this work are polymer-based and thus offer potential for large-scale, high volume manufacturing. Two different techniques are developed for microfabrication of these MEAs - laser micromachining of a conformally deposited polymer on a non-planar surface to create 3-D molds for metal electrodeposition; and metal transfer micromolding, where functional metal layers are transferred from one polymer to another during the process of micromolding thus eliminating the need for complex and non-repeatable 3-D lithography processes. In-vitro and in-vivo 3-D MEAs are microfabricated using these techniques and are packaged utilizing Printed Circuit Boards (PCB) or other low-cost manufacturing techniques. To demonstrate in-vitro applications, growth of 3-D co-cultures of neurons/astrocytes and tissue-slice electrophysiology with brain tissue of rat pups were implemented. To demonstrate in-vivo application, measurements of nerve conduction were implemented. Microelectrode impedance models, noise models and various process models were evaluated. The results confirmed biocompatibility of the polymers involved, acceptable impedance range and noise of the microelectrodes, and potential to improve upon an archaic clinical diagnostic application utilizing these 3-D MEAs.Ph.D.Committee Chair: Mark G. Allen; Committee Member: Elliot L. Chaikof; Committee Member: Ionnis (John) Papapolymerou; Committee Member: Maysam Ghovanloo; Committee Member: Oliver Bran

Probing multivalent particle–surface interactions using a quartz crystal resonator

The rise in market-approved cellular therapies demands for advancements in process analytical technology (PAT) capable of fulfilling the requirements of this new industry. Unlike conventional biopharmaceuticals, cell-based therapies (CBT) are complex “live” products, with a high degree of inherent biological variability. This exacerbates the need for in-process monitoring and control of critical product attributes, in order to guarantee safety, efficacious and continuous supply of this CBT. There are therefore mutual industrial and regulatory motivations for high throughput, non-invasive and non-destructive sensors, amenable to integration in an enclosed automated cell culture system. While a plethora of analytical methods is available for direct characterization of cellular parameters, only a few satisfy the requirements for online quality monitoring of industrial-scale bioprocesses. [Continues.

Bipolar Electroactive Conducting Polymers for Wireless Cell Stimulation

Electrochemical stimulation (ES) promotes wound healing and tissue regeneration in biomedical applications and clinical studies and is central to the emerging field of electroceuticals. Traditional ES such as deep brain stimulation for Parkinson’s disease, utilises metal electrodes that are hard wired to a power supply to deliver the stimulation. Bipolar electrochemistry (BPE) introduces an innovative approach to cell stimulation that is wireless. Developing conducting polymers (CPs)-based stimulation platforms wireless powdered by BPE bipolar will provide an exciting new dimension to medical bionics. In this project, Chapter 2 deals with development of a bipolar electrochemical activity testing system and bipolar electrochemical stimulation (BPES) system. Then, bipolar electroactive and biocompatible CPs grown on FTO substrate are successfully synthesised, modified, and characterised in Chapter 3 and Chapter 4 using the above systems prior to using for wireless cell stimulation. Furthermore, free standing and soft CP templates are developed (Chapter 5). More importantly, all these bipolar electroactive CPs have been applied to wireless cell stimulation using BPE (all research Chapters). Significant increase in both cell number and neurite growth has been demonstated, suggesting that the BPES system is highly efficient for stimulation of animal PC 12 cell and human SH-SY5Y cell. More specific information is presented in each chapter as below. In Chapter 3, a CP-based bipolar electrochemical stimulation (BPES) system for cell stimulation was present. Polypyrrole (PPy) films with different dopants have demonstrated reversible and recoverable bipolar electrochemical activity under a low driving DC voltage

Antimicrobial peptides: Powerful biorecognition elements to detect bacteria in biosensing technologies

Bacterial infections represent a serious threat in modern medicine. In particular, biofilm treatment in clinical settings is challenging, as biofilms are very resistant to conventional antibiotic therapy and may spread infecting other tissues. To address this problem, biosensing technologies are emerging as a powerful solution to detect and identify bacterial pathogens at the very early stages of the infection, thus allowing rapid and effective treatments before biofilms are formed. Biosensors typically consist of two main parts, a biorecognition moiety that interacts with the target (i.e., bacteria) and a platform that transduces such interaction into a measurable signal. This review will focus on the development of impedimetric biosensors using antimicrobial peptides (AMPs) as biorecognition elements. AMPs belong to the innate immune system of living organisms and are very effective in interacting with bacterial membranes. They offer unique advantages compared to other classical bioreceptor molecules such as enzymes or antibodies. Moreover, impedance-based sensors allow the development of label-free, rapid, sensitive, specific and cost-effective sensing platforms. In summary, AMPs and impedimetric transducers combine excellent properties to produce robust biosensors for the early detection of bacterial infectionsPeer ReviewedPostprint (published version

Sensor technologies for quality control in engineered tissue manufacturing

The use of engineered cells, tissues, and organs has the opportunity to change the way injuries and diseases are treated. Commercialization of these groundbreaking technologies has been limited in part by the complex and costly nature of their manufacture. Process-related variability and even small changes in the manufacturing process of a living product will impact its quality. Without real-time integrated detection, the magnitude and mechanism of that impact are largely unknown. Real-time and non-destructive sensor technologies are key for in-process insight and ensuring a consistent product throughout commercial scale-up and/or scale-out. The application of a measurement technology into a manufacturing process requires cell and tissue developers to understand the best way to apply a sensor to their process, and for sensor manufacturers to understand the design requirements and end-user needs. Furthermore, sensors to monitor component cells’ health and phenotype need to be compatible with novel integrated and automated manufacturing equipment. This review summarizes commercially relevant sensor technologies that can detect meaningful quality attributes during the manufacturing of regenerative medicine products, the gaps within each technology, and sensor considerations for manufacturing