Michael J. Renn

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An important strategy for realizing flexible electronics is to use solution-processable materials that can be directly printed and integrated into high-performance electronic components on plastic. Although examples of functional inks based on metallic, semiconducting and insulating materials have been developed, enhanced printability and performance is(More)
A central challenge for printed electronics is to achieve high operating frequencies (short transistor switching times) at low supply biases compatible with thin film batteries. In this report, we demonstrate partially printed five-stage ring oscillators with >20 kHz operating frequencies and stage delays <5 μs at supply voltages below 3 V. The fastest ring(More)
Organic thin-film-transistors (OTFTs) are drawing much attention as they have attributes such as structural flexibility, low-temperature processing, large area coverage, and low cost, which make them attractive for large-area electronics. Various forms of OTFTs can enable applications that were not achievable using traditional inorganic transistors and/or(More)
Laser-induced optical forces can be used to guide and deposit 100 nm - 10 microm-diameter particles onto solid surfaces in a process we call 'laser-guided direct writing'. Nearly any particulate material, including both biological and electronic materials, can be manipulated and deposited on surfaces with micrometer accuracy. Potential applications include(More)
To perform their myriad functions, tissues use specific cell-cell interactions that depend on the spatial ordering of multiple cell types. Recapitulating this spatial order in vitro will facilitate our understanding of function and failure in native and engineered tissue. One approach to achieving such high placement precision is to use optical forces to(More)
Controlling adhesion of living animal cells plays a key role in biosensor fabrication, drug-testing technologies, basic biological research, and tissue engineering applications. Current techniques for cell patterning have two primary limitations: (1) they require photolithography, and (2) they are limited to patterning of planar surfaces. Here we(More)
The fabrication and characterization of printed ion-gel-gated poly(3hexylthiophene) (P3HT) transistors and integrated circuits is reported, with emphasis on demonstrating both function and performance at supply voltages below 2 V. The key to achieving fast sub-2 V operation is an unusual gel electrolyte based on an ionic liquid and a gelating block(More)
We present an easily applicable and inexpensive method for patterning cells on arbitrary surfaces including biological gels with little loss of viability or function. Single-cell suspensions of human umbilical vein endothelial cells and NIH 3T3 fibroblasts were sprayed with an off-the-shelf airbrush through a mask to create 100-microm scale patterns on(More)
Thin film transistors are at the heart of integrated circuits. Modern computer processor chips can contain more than 2 billion transistors. Such chips are currently fabricated by expensive lithography processes and fabrication facilities can cost more than one billion US dollars. In a future era of cheap, disposable electronics such cost structures will not(More)
Printed Circuit boards (PCBs) are traditionally fabricated using subtractive technologies such as lithography and etching. Discrete passive and active components are typically attached by pick and place and then connected using wire bonding and soldering. In this paper we show that direct printing can replace many of the traditional steps and consequently(More)