03/31/2022
By Sokny Long

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a doctoral dissertation defense by Edward Fratto on “Printed Assembly and Nanosoldering of Core-Shell Nanowires and Graphene Oxide for Environmental Sensing and E-Textile Applications.”

Ph.D. Candidate: Edward Fratto
Defense Date: Thursday, April 7, 2022
Time: 1 to 3 p.m. EST
Location: This will be an in person defense in ETIC 445, and also a virtual defense via Zoom. Those interested in attending should contact Edward_Fratto@student.uml.edu and committee advisor, Zhiyong_Gu@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor) Zhiyong Gu, Professor, Chemical Engineering, University of Massachusetts Lowell

Committee Members:

  • Dongming Xie, Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Hongwei Sun, Professor, Mechanical and Industrial Engineering, Northeastern University
  • Teiichi Ando, Professor, Mechanical and Industrial Engineering, Northeastern University

Brief Abstract:
Ongoing miniaturization efforts in electronic device manufacture have driven component study to the nanoscale, sparking interest in nontraditional packaging strategies and substrates for device design such as smart ‘e-textiles’ devices which translate traditional circuit manufacturing strategies onto flexible textile materials to integrate device functionality. We provide an investigation into the formulation of nanosolder-composite suspensions and inks for the printing of conductive signal-carrying channels and chemiresistive sensing elements enhanced by novel low-temperature soldering. This work reports the development of a synthesis technique for a core/shell nanowire structure capable of permanent soldered interconnection following magnetic self-assembly of desired matrix hierarchies. Multi-segment nanowires consisting of sequential gold-nickel-gold segments were synthesized via templated electrochemical deposition in an anodic aluminum oxide (AAO) template. Gold-selective deposition was accomplished via modification of the nickel surface with a protective carboxylic acid monolayer, followed by a ‘flipped’ aqueous chemical reduction of tin precursor solution in aqueous sodium borohydride. Gold-selective tin deposition was confirmed via SEM and EDS. Melting of the solder payload was achieved via infrared radiation in a flux atmosphere with an associated resistance drop of 99%. After soldering, the core/shell nanowires acted as an ammonia sensor with linear response in the 0-100ppm range. Additionally, low melting temperature tin/indium nanosolder particles were synthesized and formulated into conductive inks with graphene oxide at various loadings, then applied to fabric blend materials by dip-dry coating and screen printing to establish gas-sensing functionality. Exposure to infrared heating enabled targeted soldering of graphene oxide platelets without harming the fiber structure, improving conductivity and enhancing the sensitivity and detection limit of the material for gaseous ammonia. This work demonstrates robust, low-temperature soldered interconnection on a conductive textile platform for improved mechanical reliability and sensitivity of fabric-mounted sensors.

All interested students and faculty members are invited to attend the defense in person or via remote access.