Freeform Fabrication of Electroactive Polymer Actuators and Electromechanical Devices

In pursuit of the goal of producing complete electromechanical systems entirely via solid freeform fabrication, we are developing a library of mutually compatible, functional, freeform elements. Several essential elements – actuation, sensing, and control electronics - still remain to be incorporated into this library. Conducting polymers (CP) are a class of materials which can be used to produce all of these functionalities. Meanwhile, research into actuatable “smart” materials has produced other candidate materials for freeform fabricated actuators that are compatible with our library. We have succeeded in manually producing air-operable actuators that have processing and operating requirements that are compatible with our power source and mechanical component library elements. A survey of candidate actuator materials is presented, experiments performed with two types of actuator materials are described, and complete SFF-producible actuator devices are demonstrated.Mechanical Engineerin

Freeform Fabrication of Ionomeric Polymer-Metal Composite Actuators

Ionomeric polymer-metal composite (IPMC) actuators are a type of soft electromechanically active material which offers large displacement, rapid motion with only ~1V stimulus. IPMC’s are entering commercial applications in toys (Ashley 2003) and biomedical devices (Soltanpour 2001; Shahinpoor 2002; Shahinpoor, Shahinpoor et al. 2003; Soltanpour and Shahinpoor 2003; Soltanpour and Shahinpoor 2004), but unfortunately they can only actuate by bending, limiting their utility. Freeform fabrication offers a possible means of producing IPMC with novel geometry and/or tightly integrated with mechanisms which can yield linear or more complex motion. We have developed materials and processes which allow us to freeform fabricate complete IPMC actuators and their fabrication substrate which will allow integration within other freeform fabricated devices. We have produced simple IPMC’s using our multiple material freeform fabrication system, and have demonstrated operation in air for more than 40 minutes and 256 bidirectional actuation cycles. The output stress scaled to input power is two orders of magnitude inferior to that of the best reported performance for devices produced in the traditional manner, but only slightly inferior to devices produced in a more similar manner. Possible explanations and paths to improvement are presented. Freeform fabrication of complete electroactive polymer actuators in unusual geometries, with tailored actuation behavior, and integrated with other freeform fabricated active components, will enable advances in biomedical device engineering, biologically inspired robotics, and other fields. This work constitutes the first demonstration of complete, functional, IPMC actuators produced entirely by freeform fabrication.Mechanical Engineerin

Printing Embedded Circuits

Automated manufacturing technologies such as freeform fabrication can greatly reduce the cost and complexity of infrastructure required to manufacture unique devices or invent new technologies. Multi-material freeform fabrication processes under development have the potential to automatically build complete functional devices including electronics. Making this technology available to creative individuals will revolutionize art and invention, but requires extensive simplification and cost reduction of what is still a laboratory technology. The combination of a Fab@Home Model 1 personal fabrication system and commercially available materials allows the demonstration of simple and inexpensive freeform fabrication of functional embedded electrical circuits, and useful devices. Using this approach, we have been able to demonstrate an LED flashlight, functional printed circuit boards in 2-dimensions and 3- dimensions that are actually entirely printed, and a child’s toy with embedded circuitry. These results, and the materials and methods involved in producing them will be presented in detail.Mechanical Engineerin

Compounding Crimes: Time for Enforcement

Although many crimes apparently are compounded, prosecution for compounding itself is rare. This note explores why, and analyzes the present state of American compounding law. It suggests that condonation of compounding may hinder the fight against white collar crime. It also critically examines the Model Penal Code approach to compounding, and as an alternative it proposes more vigorous enforcement of existing compounding laws, coupled with an increased availability of officially-sanctioned compromise for most crimes

Printing Food

This paper examines the possible applications of food as a raw material in freeform fabrication, and provides several demonstrations of edible three-dimensional objects. The use of edible materials offers several advantages: First, it opens the door to the application of SFF technology in custom food industry, such as manufacturing of complex confections with specialized geometries and intricate material compositions. For pedagogical purposes, edible materials provide an easily accessible, nontoxic and low cost way to experiment with rapid prototyping techniques using educational systems such as Fab@Home. For more traditional SFF technologies, food materials with appropriate rheological properties can serve as sacrificial, bio-degradable, bio-compatible or recyclable materials for structural support and draft-printing. We have used the Fab@Home personal fabrication system to produce multi-material edible 3D objects with cake frosting, chocolate, processed cheese, and peanut butter. These are just indicative of the range of potential edible materials and applications.Mechanical Engineerin

Object Augmentation for the Visually Impaired Using RP

We demonstrate the application of rapid prototyping technology to augment every-day objects for the visually impaired. A freeform fabricator was used to print a tactile alphabet on multiple surfaces including paper, plastic, and metal. We have identified and experimented with multiple non-toxic materials and analyzed the dimensional tolerance, repeatability, and adhesion characteristics on multiple surfaces. Printing time for 1x1cm embossed letters varied from 14 to 52 seconds. More broadly, these experiments open the door to RP applications that involve custom product adaptation to address disabilities.Mechanical Engineerin

Colonic ulcerations may predict steroid-refractory course in patients with ipilimumab-mediated enterocolitis

To investigate management of patients who develop ipilimumab-mediated enterocolitis, including association of endoscopic findings with steroid-refractory symptoms and utility of infliximab as second-line therapy

Ipilimumab administration for advanced melanoma in patients with pre-existing Hepatitis B or C infection: a multicenter, retrospective case series

Ipilimumab is a fully human, monoclonal antibody directed against Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) that has demonstrated a survival benefit and durable disease control in patients with advanced melanoma. Ipilimumab is associated with potentially serious immune-related adverse events, including autoimmune hepatitis. Because clinical trials of ipilimumab excluded patients with pre-existing hepatitis B or C infection, there is a paucity of data on the safety of ipilimumab administration to that patient population. Here, we report the largest case series to date of patients with hepatitis B or C who received ipilimumab for advanced melanoma. Two of the nine patients described in this case series experienced fluctuations in their liver function tests (LFTs) and were subsequently treated with corticosteroids. Although this is a small series, the rate of hepatotoxicity appears similar to what has been seen in the general population treated with ipilimumab, and the ability to administer ipilimumab did not appear to be affected by concomitant hepatitis B or C infection. The use of ipilimumab in patients with metastatic melanoma who have pre-existing hepatitis can be considered among other therapeutic options