UV - vis Spectroscopy with the WheeTrometer

August 2020:  This project is still in the prototyping stage. 

     The WheeTrometer is a miniature uv-vis spectrometer with a crossed Czerny-Turner configuration.  It uses a Toshiba TCD1304 CCD detector and a Texas Instruments TM4C123 microcontroller.  Light dispersion incorporates a 1200 line/mm reflection grating with a 500 nm blaze angle.  Our optical slits have a 0.1 mm width.  Spectra shown on this page was collected using an early spectrometer with 12 bit intensity resolution and the wavelength resolution in the 1-5 nm range.  We are currently working to increase the intensity resolution by incorporating a high resolution Analog to Digital Converter (ADC).

     The screen shot below shows the spectrum of a compact fluorescent lamp recorded with a 2019 WheeTrometer prototype.

The body of the spectrometer can be printed using a standard 3D printer.  The colimating mirror is 20 mm in diameter with a focal length of 100 mm.  The focusing mirror is rectangular, 20 x 50 mm with a 50 mm focal length.

3d Printed spectrometer body
Optics kit: Slit, colimating mirror, grating and focusing mirror
2019 Microcontroller board (12 bit resolution)
2020 24 Bit ADC board
Video Demonstrating WheeTrometer Assembly:
Video demonstrating software and introducing our UV-vis lamp
Video demonstrating our calibration software.

Sample holder:  We plan to offer two sample holder configurations: one for standard 1 cm cuvettes and a second, Z-configuration flow cell.  Each will screw directly to the spectrometer body, just outside the slit.

Software:  We are working to optimize and improve the user interface and firmware.  As of June 2019 our user interface (GUI) will do the following tasks:

     1.  connect automatically to the spectrometer over USB.

     2. set run parameters such as:

          2a. integration time,

          2b. number of acquisitions to average before reporting, and 

          2c. number of pixels to average

     3.  initiate spectral acquisition

     4.  display recorded data

     5.  save data files in csv format

We are now working to incorporate multi-datafile protocols, import saved spectra, conversion of data types (raw intensity to absorbance) and various math manipulations.  These we have worked out in our other projects so we don't foresee any major obstacles.

Light sources:  Not fully developed.  We intend to offer different versions of the spectrometer that will employ different light sources.  We are currently working on a uv-vis spectrometer and light source that will interface via standard SMA905 fiber optic connectors. We also plan to develop instruments where the source connects directly to the spectrometer.  Our UV-vis light source will employ deuterium and halogen lamps.  A dedicated visible spectrometer may be developed that relies on leds as light source.

 

Availability:  Kits are currently available.  We will offer an optics kit containing the mirrors, slit and grating.  We currently offer an electronics kit with the 2019 12 bit resolution microcontroller board.  The microcontroller will come with the firmware installed.  User interface will be available from our download page or on usb drive.  STL files for 3D printed plastics will be available.

Costs:  We offer the spectrometer as a set of kits for considerably less than the price of other available spectrometers.  Our combined spectrometer kit (containing both optics and electronics) is available for $250 USD.  We can supply either the electronics or optics kits.  Contact me for a quote.  We hope we will be able to supply the UV-vis light source for $1000 USD. 

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WHAT'S UP?

CURRENT PROJECTs

 

August 2020:

  Work during summer 2020 focused on the WheeTrometer spectrometer and on the WheeStat potentiostat.

  The spectrometer is coming along.  We are currently working to improve the intensity resolution by adopting a high resolution analog to digital converter.

  Our work on the WheeStat is focused mostly on increasing the current output available.  In addition, we hope to increase the range of frequencies that can be obtained by adding a digital to analog converter.

August, 2017:

   Work during summer 2017 focused on two projects, the WheeStat potentiostat and the stopped flow spectrometry apparatus.

  •    Work on the WheeStat included changes to the user interface, firmware and hardware.  The newest version of the user interface, WheeStat6.0c, has a new zoom feature and a few bugs from the older interface have been fixed.  We believe the new hardware will be out by the end of 2017.  The new hardware will have an improved method for turning off applied voltatage between experiments.  This is a hardware fix that requires modification of the firmware as well.  We will offer an add-on for our earlier hardware versions that incorporates this feature.  Addditional changes include increased current ranges and the potential for significantly increased scan rates.

  • Work on the stopped flow spectrometry project focused on increasing the injection speed.  Our initial effort focused on developing a rack and pinnion drive for the syringes.  This improved injection speed relative to the lead screw drive but failed to meet target speeds due, we believe, to limited torque provided by the small NEMA 17 motors we chose.  Our next attempt employed larger NEMA 23 motors.  These have significantly higher torque.  Unfortunately, our flow cell was unable to contain the generated pressure and began leaking.  Current efforts are focused on developing a lab-built UV-vis cell that will hold higher pressures.

 

September, 2016:

  • Our work to automate solid phase synthesis of peptides / DNA, etc has progressed well, although the chemistry is more involved that I had origianally thought.  We have made our first attempt at synthesis of a cystiene modified tri-peptide

  • Our application for recognition by the IRS as tax exempt under 501(c)3 has been approved.

  • We have begun work on a low cost visible spectrometer that will use home built reflective optics.

  • We are working on developing a stopped flow kinetics instrument based on commercially avialable spectrometer.  Our current prototype is able to acquire spectra within 120 ms of mixing.  This dead time appears to be limited by the power of the motors we used.  We are investigating the use of larger motors and hope to get the dead time down to below 12 ms.

 

EVENTs

6-10

PITTCON CONFERENCE & EXPO 2016

 

Presentation  in Atlanta, GA,  March 6-10, 2016

Our talk was well recieved at the Educational symposium at PittCon

CONTACT

4989 Tilley Creek Road

Cullowhee, NC 28723

Tel: 828-293-7781
 

 

Mail:  summers@wcu.edu

j6summers@gmail.com

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21

2016 SE REGIONAL ACS MEETING

Oct 23-27, SouthEast Regional Meeting of the American Chemical Society, Columbia SC

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