Research Infrastructure

The following Institute support resources are central to Rowland's ability to maintain a dynamic research environment.

  • Machine and Model Shop - The Rowland shop offers fabrication of one-of-a-kind instruments and components. The shop includes two numerically-controlled milling machines, two lathes and various brakes, grinding machines, and all that is necessary to fulfill the most complex research requirements. A welding facility provides the capability to rapidly fabricate ultrahigh vacuum (UHV) components.

 

  • Electronics Engineering Laboratory - Winfield Hill directs the Electronics Engineering Lab, which has three members and designs and fabricates custom instruments to advance mankind's progress in science. Over 400 separate designs have been produced in the past 12 years.

        

  • Computation and Information Technology - As well as the usual email, VPN, and file-storage services, the Rowland Institute offers personal assistance with all theoretical or practical problems related to computing, modelling, mathematics, and statistics. To help with common computing tasks, the Institute has site licenses for LABView and AutoCAD (in addition to the numerous programs licensed by Harvard or FAS).
  • Our Facility - Laboratories and shared facilities are built as needed for the current research projects.

       

    Computation and IT

    General Computation

    As well as the usual email, VPN, and file-storage services, the Rowland Institute offers personal assistance with all theoretical or practical problems related to computing, modelling, mathematics, and statistics. To help with common computing tasks, the Institute has site licenses for LABView and AutoCAD (in addition to the numerous programs licensed by Harvard or FAS).

    Rowland NMR Toolkit

    The Rowland NMR Toolkit (RNMRTK) is a software package for processing multidimensional NMR data and a platform for the facile implementation of novel NMR data processing methods. In addition to efficient and robust algorithms for traditional signal processing methods such as linear prediction extrapolation and discrete Fourier transformation, RNMRTK implements a very powerful and general algorithm for computing maximum entropy (MaxEnt) reconstruction, which is especially useful for processing non-uniformly sampled NMR data. RNMRTK provides rudimentary tools for analyzing and displaying spectra, but is best used in conjunction with more powerful and general-purpose analysis software. RNMRTK interoperates with nmrPipe, nmrDraw, XEASY, Sparky, NMRview, and other NMR software packages. .


    Video conferencing

    The Rowland Institute offers two video-conferencing setups, both using standard communications protocols. One has a 15-inch screen and is suitable for a single person or a small group. The other has dual 42-inch screens, providing the ability to display digital content on one screen along with a large group or roomful of people on the other screen.

    Electronics Engineering Laboratory

    Winfield Hill is Director of Electronics Engineering at the Rowland Institute. He directs the Electronics Engineering Laboratory, which consists of three full-time people plus student employees. 

    The Laboratory is fully appointed with three instrumentation benches (including one for use by other Institute members), an extensive suite of electronic test and measurement instrumentation, and a substantial inventory of electronic parts, e.g., including about 850 different types of ICs. 

    The Electronics Engineering Lab designs and fabricates most of the critical electronic instrumentation found throughout the Institute. Over 500 separate designs have been produced in the past 12 years. The electronic controls for both the scanning tunneling microscope (STM) and Ion Trap experiments are examples of the Lab's unique instrumentation, providing capabilities not available elsewhere. Lena Hau's well-known Bose-Einstein condensation experiments, including slowing and stopping light for 10 microseconds, were performed here at the Rowland Institute in her Atom-Cooling Laboratory, located directly below our lab. Her successful experiments utilized about 80 instruments, comprising over 65 separate designs, specially created by the Electronics Engineering group.

    Current Members

    Project Highlights

    Current Members

    Chris Stokes

    Electronics Engineering Laboratory
    Electronics Instrumentation Engineer
    Rowland Institute at Harvard
    Harvard University
    100 Edwin H. Land Blvd.
    Cambridge, MA 02142
    Tel: 617-497-4635
    Fax: 617-497-4627


    Chuck Fisk

    Electronics Engineering Laboratory
    Associate Engineer
    Rowland Institute at Harvard
    Harvard University
    100 Edwin H. Land Blvd.
    Cambridge, MA 02142
    Tel: 617-497-4635
    Fax: 617-497-4627

    Project Highlights

    RIS-517 - Tweezer Squeezer - Nitinol, or Muscle Wire®, has a long history as a fascinating “solution looking for a problem.” For example, unlike other metals Nitinol shrinks rather than expands when heated. Its most famous application is in flapping butterfly wings.

    Here's an exceptionally clever creation using Nitinol by Chris Stokes: An electronic tweezer for grabbing very small objects.

    RIS-418, RURB - Developed for Bob Savoy for his fMRI research at the Rowland Institute.

    This two-hand ten-button USB interface has become popular among scientists the world over.

    RIS 517

    RIS-517 - Tweezer Squeezer, by Chris Stokes

    One of the physicists at Rowland, Mike Burns, was looking for a way to hold micrometer-scale wires for experiments on electromigration. The requirement was to be able to grasp one of these wires with an existing micro-manipulator X-Y-Z positioning system, without introducing human-scale vibration. Tweezers exist which can accomplish this on a micron scale, but these are quite expensive, so we decided to see if we could produce something a little better.
                          
     
     
    Development
    Part of the requirements were for the tweezers to mount easily on and off the positioning system, and perhaps to be hand-usable. Initially, I tried a straight-forward approach with a small motor and a fine pitch bolt mounted to it.

    I had difficulty with the motor size and torque, given the need to overcome stiction for the fine pitch we wanted to use. Eventually, the motor began to outsize the tweezers themselves and I started looking for a different solution.

     
     
    Muscle Wire®
    Nitinol wire (often called Muscle Wire®) looked like a reasonable answer. The particular tweezer we chose, Technitool Stainless Steel #7's, required approximately 100 grams for closure. Maximum pull for 0.006" dia. Nitinol is 330 grams. That provided a decent margin for error, and should conservatively allow the wire run for a few hundred thousand cycles. Mike was working with thin wire, about 3 microns, so a reduced-distance tweezer opening of 0.15” would be more than sufficient. The wire contracts by about 5% of its length, so 20 x 0.150 gives a minimum 3 inches needed for closing the tweezers.

                             

    I planned to run the wire out and over a quarter-round piece of teflon, down through a hole in the tweezers, double back around and back up over the teflon quarter-round. The wire must remain insulated from the tweezers, so I mounted it on a nylon bolt set perpendicular to the tweezer's long axis. This bolt sits on tiny bracket that allows you to adjust closure and tension.

     
    Terminating and joining the Nitinol was a bit of a challenge. Soldering is unreliable, as the Nitinol has a lot of oxide which makes things difficult. Clamping between bolts seemed suspect to me as the wire would be heat-cycling, so I chose to terminate with crimping lugs and then make a conductive contact to the lugs.

     
    Three inches of 0.006 Nitinol gives about 3.8 ohms resistance. The Images SI folks say that 400mA through the wire when it's sitting at room temperature will raise the temperature sufficiently to make it contract. 400mA/3.8 ohms = 1.52V drop that I should expect across the wire.

    Electronics
    I asked Win about a good controllable current source, and he recalled one he'd written about on a news group years ago.

     Win's current source required a current sink of a few milliamps, which we implemented with a 10k resistor, but this wasn't quite effective at low voltages, so we made a better one with a 2N3904 aimed at about 4mA. This makes a more flexible single-supply current source. I used RadioShack's elegant little “power supply in a plug” (6V 1800mA, pin 273-1763).


    Refinement
    The first problem I encountered was the fulcrum point. I made it out of a nylon screw cut in half to give a gentle turn to the Nitinol wire, and then epoxied it onto the bottom surface of the tweezer. The melting point for nylon is about 400F, but with pressure, and the thin wire, it seemed to eat into it at a much lower temperature, even around 170. The nylon fulcrum bolt then bound up the Nitinol wire and the tweezers wouldn't close.

    To solve this problem I swapped that bolt out for a metal pin with a teflon sleeve. This gave a bit tighter radius, but better temperature resistance and less flex.

    The next issue was very slow action, like 1/2 a second to close, and 5 seconds to open, plus about a minute to recover to a fully open position. I addressed this, probably in the wrong way, in retrospect. I changed to a thicker diameter Nitinol wire and ran more current through it. This did close quicker, but it still didn't open quickly, so I added a bit more resistance right at the closure point of the tweezer, by gluing in a bit of open-cell foam to the inside of the tweezers. This gets the tweezer started opening a bit quicker, more like a second to open, and five seconds to fully recover.

     



    Next time I'd make a longer Nitinol wire run, I think. Start with a normally closed, reverse action tweezer that is teflon coated. Opening force for that would be more predictable than closure force. A longer Nitinol wire would also relax quicker.



    Conclusion
    The finished Tweezer Squeezer works well, and takes on the order of a 1/2 second to close, and about 2 seconds to open. The setup works best if the closure point is tuned by turning the pot, watching for closure, and then using the on/off switch from then on. Mike says he's eagerly awaiting the improved version.

     
    REV 2
    In this version, I allowed for a longer run of the nitinol wire by zig-zagging it along the side of the tweezer. I epoxied a series of small copper tubes with teflon tubing as insulation. The wire routes back and forth like a shoelace. This gives a little more length and thus cools a little more quickly. Mike's impression is that it's much improved.

    Library

                     

    The Rowland library offers a quiet place to search the stacks and to read the most recent popular scientific journals,  for those who enjoy turning pages.  We also enjoy both physical and internet access to the Harvard University Libraries.

    Machine and Model Shop

    This page has been updated to a separate site. Please go to - Rowland's Machine and Model Shop.