Jaeho Park

Direct metal micropatterning on needle-type structures towards bioimpedance and chemical sensing applications

Direct metal patterning methods, such as screen printing, inkjet printing and gravure/flexography printing, are widely used to form electrodes or interconnections for printed electronic devices due to their inexpensive, simple and rapid fabrication as compared to vacuum-based conventional metallization processes. Here, we present direct metal patterning by modified screen printing on the curved surface of needle-type rod structures (i.e. rods with radius of ??<?1?mm). We achieved various microscale patterns such as straight lines, zigzag lines, wavy lines and alphabetic words with a minimum width of 70??m on the surface of the rod. Also, four pairs of line patterns were printed on the single rod for electrical interconnection. Printed patterns on the surface of the rod were used as electrodes for the control of a light emission diode (LED) as well as the real-time electrochemical impedance spectroscopy of electrolyte solutions and solid objects by the rod insertion. Furthermore, needles with multiple pairs of microelectrodes were used to measure the electrical impedance of biological samples such as fat and muscle tissues of porcine meat. In addition, a needle-type probe sensor with gas sensing capability was demonstrated by using a needle with printed Ag electrodes and Pd thin films.

A multi-pair electrode based impedance sensing biopsy needle for tissue discrimination during biopsy process.

We demonstrate the biopsy needle integrated with multi-pair electrode based impedance sensing device for biological tissue discrimination. The impedance sensing biopsy needle has several pairs of electrodes which enable the selective tissue analysis during biopsy process. In order to verify the usefulness of the device, we demonstrate the conductance measurement of various saline solutions and the real-time conductance monitoring of soft elastomeric materials during the needle insertion. Finally, the tissue discrimination of porcine meat tissues during the needle insertion was successfully carried out.We demonstrate the biopsy needle integrated with multi-pair electrode based impedance sensing device for biological tissue discrimination. The impedance sensing biopsy needle has several pairs of electrodes which enable the selective tissue analysis during biopsy process. In order to verify the usefulness of the device, we demonstrate the conductance measurement of various saline solutions and the real-time conductance monitoring of soft elastomeric materials during the needle insertion. Finally, the tissue discrimination of porcine meat tissues during the needle insertion was successfully carried out.

Biopsy Needle Integrated with Electrical Impedance Sensing Microelectrode Array towards Real-time Needle Guidance and Tissue Discrimination

A biopsy needle with electrical impedance sensor array based on stainless steel microelectrodes (EIS needle) was developed for real-time four electrode measurement and multi-spot sensing of tissues during the biopsy process. The sensor performance was characterized by using saline solutions with various concentrations, which proved accurate, stable and reliable electrical impedance measurement. The capability of impedance-based tissue sensing was verified by the conductivity measurement of agarose hydrogel based phantom mimicking cancer tissue. Furthermore, multi-spot impedance sensing during needle insertion was demonstrated using porcine meat with muscle and fat layers, which exhibited a clear discrimination between different types of tissues. Also, the electrical impedance difference between normal and fatty livers of mouse model was measured by the EIS needle. We could successfully demonstrate that the EIS needle can provide localized and accurate characterization of biological tissues at the needle tip.

Polyaniline-polystyrene nanofibers directly written on cheap flexible substrates by electrospinning, a low-cost and sensitive hydrogen sulfide gas sensor

This paper presents a novel hydrogen sulfide (H2S) gas sensor based on polyaniline-polystyrene nanofibers doped by camphorsulfonic acid (HCSA). The obtained polyaniline (PAni) sensor has good sensitivity, low detection limit and very good recovery time compared with the previously proposed H2S sensors based on PAni. The sensor was fabricated by a simple and cheap procedure on cheap paper and polyimide substrates by electrospinning. Simplicity of the synthesizing method, together with the cheap and flexible substrates provide a low-cost and room temperature H2S gas sensor that is unique in terms of sensitivity, detection limit and recovery time.

Development of multi-spot impedance sensing biopsy needle based on attachable and flexible sensor film

We demonstrate the biopsy needle capable of multi-spot impedance sensing based on attachable and flexible sensor film. In order to directly integrate sensor electrodes into curved surface of biopsy needle, attachable and thin polyimide substrate was used. Sensor electrodes were easily manipulated due to advantage of conventional microfabrication technique and this enable capability of multi-spot impedance sensing. To verify validity of proposed method, attachability of sensor film and real-time response of multi-spot sensing of fabricated biopsy needle was investigated.We demonstrate the biopsy needle capable of multi-spot impedance sensing based on attachable and flexible sensor film. In order to directly integrate sensor electrodes into curved surface of biopsy needle, attachable and thin polyimide substrate was used. Sensor electrodes were easily manipulated due to advantage of conventional microfabrication technique and this enable capability of multi-spot impedance sensing. To verify validity of proposed method, attachability of sensor film and real-time response of multi-spot sensing of fabricated biopsy needle was investigated.