Maloney picture

John M. Maloney, Ph.D.

Prototyping, technical editing, and entropy interpretation

Research associate / research scientist /
research affiliate (2006-2017)
MIT Laboratory for Material Chemomechanics

Senior MEMS engineer (2001-2005) 
MicroCHIPS, Inc.
Engineer-in-residence (2001-2005)
MIT Microsystems Technology Labs

February 2020: Updated technical note on mechanics: Let’s not overrate Young’s modulus.
November 2019: A fitting line that “boings” into place—with a digression on spring-mass-dampers, vibration and control theory, and integral transforms.
May 2019: New technical notes on machine learning: Support vector machines, part 1; part 2.
August 2018: New technical note on thermodynamics: When Nature takes the square root.
June 2017: New paper published in Nature Materials; updated pictures and publications.
September 2016: Updated list of errata and new insights.
July 2015: Sampoerna students kindly summarized my invited talk in Jakarta.

I answer scientific and engineering questions as Chemomechanics on Stack Exchange and on Reddit. Some of my answers address:

Why is energy minimized?
Why is stress a tensor, not a vector?
Can Hooke's Law be derived?
What happens if we freeze ice in an unexpandable box?
What happens if we pull a metal bar for a very long time?
Is there an intuitive definition of the chemical potential?
Why does the temperature stay constant during a phase change?
Why is there a maximum humidity?
Does the surrounding pressure affect the vapor pressure?
Why are metals ductile?
How do gases stratify?


1999 lab picture

Publications and pictures are here.
Technical notes on machine learning:
  • Support vector regression applied to Raman spectra (in preparation): Part 1 (maximum margin linear classifiers, transformation to achieve separability, Hesse normal form, quadratic programming optimization, convex hulls); Part 2 (Lagrange multipliers, transformation to the dual form, the kernel trick, slack variables).
Technical editing notes:
3-D stress state Technical notes on mechanics:
Linda Fleming, Smoke Creek (2009) Technical notes on thermodynamics:
Blebbing mesenchymal stem cell Technical notes and videos on biology:
Faith Wilding, Crocheted Environment (1972, 1995) Technical notes on statistics:
Programming exercises Delving into Python: a fitting line that “boings” into place (with a digression on spring-mass-dampers, vibration and control theory, and integral transforms), a touch-switch-activated random Steely Dan player on a Raspberry Pi, and a four-item kitchen timer on a tablet.

Optical profilometry image of buckled thin film

I’ve collected a variety of thin film patterns and the fantastic variety of terms used to describe them.
Prototyping exercises Prototyping demonstrations: polished brass letters that magnetically trigger LEDs.
Chemomechanics logo motifs The origins and motifs of the chemomechanics logo.
Peter and Paul paper-folding trick A brief survey of the Peter-and-Paul paper-folding trick, and my own version.
Cell schematic My doctoral research on the chemomechanics of biological cells (thesis, 7MB) was performed in the Van Vliet Group in the Department of Materials Science and Engineering at MIT under co-advisors Prof. Krystyn Van Vliet and Prof. Robert Langer.
Cambridge Science Festival poster One of my images of cells could be seen up and down Massachusetts Avenue in Cambridge for several years, before the laminated posters bleached and disintegrated.
Notebook sketch My experience with MIT's oral qualifying exam in materials science and engineering.
Equirectangular map Mapping our round-the-world trip programmatically using different global projections.
Controlled-exposure microchip A controlled-exposure technology is described here in an adapted excerpt from my 2006 MEng thesis.

MicroCHIPS logo

From 2001 to 2005 I worked for MicroCHIPS, Inc., a Boston-area bioMEMS company. This extended abstract describes the state of the technology in 2003. We published this report of preclinical testing in Nature Biotechnology in 2006.
In 2012, the common stock underwent a 100-to-1 reverse split, making most employees' shares worthless; in 2018, as the company essentially went out of business, the very new CEO sought for herself a Section 280G payment—also known as a golden parachute payment—of $1.2 million.

3DMEMS platform

One of my areas of research at the University of Maryland was 3-D microfabrication.

Thermal actuator

The other was electrothermal actuation. In this summary, I derive an equation for estimating the first-order time constant of a microfabricated suspended beam, which we published in the Journal of Micromechanics and Microengineering.

JMM bookshelf

My thoughts on philosophy, logic and teaching are well represented here.

© Copyright John M. Maloney.