After a few productive years working at companies, I decided to try something different and work for myself. I'm available for hire through my consulting business,
Vonk. In my free time I work on personal projects and enjoy the Central Oregon outdoors.
I worked at Apple for about two and a half years, performing a number of roles and leaving as a Senior Sensor System Architect.
Summary:
- Technical lead for new sensor and actuator architectures (ICT4)
- Engineering manager for the 3D Touch EE architecture team on iPhone X (EM1, EM2)
- Transitioned from on-site manager to remote individual contributor (ICT5)
- Proposed and developed new technologies for future products
- Consulted with sensor/actuator teams throughout Apple to solve critical problems
- Misc: hiring, mentoring, software infrastructure, docs, factory bringup
After graduating from school, I worked at SiTime for nearly four years, leaving as a Principal MEMS Development Engineer.
Summary:
- Technical lead for MEMS resonator design/characterization and in-house design software tools
- Managed a team of three remote engineers in MEMS design and software development
- Trained and mentored all seven subsequent MEMS hires
- Worked cross-functionally with circuits, systems and test groups (ASIC architecture, DFT, FA)
- Invented new core technologies and spearheaded their development
I was a PhD student in the
Stanford Microsystems lab where I developed scientific instruments for the study of touch and hearing. These problems are challenging because our bodies are very good sensors - far better than most of the tools that we use to probe them. For example, the auditory hair cells in our ears can sense pN-scale forces, roughly the force required to break a hydrogen bond.
The main focus of my research was designing and fabricating a better tool for studying the mechanics and kinetics of mammalian hair cells. Key performance requirements included a spring constant of 1 pN/nm, a resonant frequency of up to 200 kHz with similar actuation bandwidth, pN-scale integrated force noise, and compatibility with operation in saline.
Towards this goal I developed new methods for the design and modeling of piezoresistive cantilevers. Next, I integrated the sensors with novel on-chip piezoelectric or thermal actuators, and fabricated the devices in the
SNF. I designed both the device layout and readout circuitry to allow for simultaneous actuation and sensing with minimal crosstalk. The final result was a family of force probes with all performance metrics 10-20x better than all work to date.
Details of the thermal, mechanical and electrical design of the force probes can be found in my publications and thesis. You can find slides from the majority of my academic presentations
here.
While at Stanford I also wrote a book with my advisor,
Piezoresistor Design and Applications. It was published by Springer in 2013 and covers everything from fabrication process options to numerical design optimization methods.
Here is my
resume.
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Piezoresistor design and applications
J.C. Doll, B.L. Pruitt
Microsystems and Nanosystems Series, Springer, 2013.
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Force sensing optimization and applications
(pdf)
J. C. Doll, S.-J. Park, A.J. Rastegar, N. Harjee, J.R. Mallon Jr., G. Hill,
A.A. Barlian and B.L. Pruitt
Advanced Materials and Technologies for Micro/Nano-Devices, Sensors and Actuator, Springer, 2010.
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MEMS resonator
C.I. Grosjean, N. Miller, P.M. Hagelin, G.C. Hill, J.C. Doll
US20240223151A1 (granted)
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Piezo-actuated MEMS Resonator
J.C. Doll, P.M. Hagelin, G.C. Hill, N. Miller, C.I. Grosjean
US20240223151A1 (granted)
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MEMS resonator with beam segments having predefined angular offset to each other and to resonator silicon crystal orientation
R.M. Berger, G.C. Hill, P.M. Hagelin, C.I. Grosjean, A. Partridge, J.C. Doll, M. Lutz
US11897757B1 (granted)
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Wireless Charging System With Temperature Sensor Array
J.S. Smith, B. Shahsavari, J.E. Mattingley, J.C. Doll, S.P. Hotelling, S. Seth, D.J. Adams, M.A. Cretella
US20200076244A1 (granted)
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Micromechanical resonator
J.C. Doll, N. Miller, C.I. Grosjean, P.M. Hagelin, G.C. Hill
US10218333B2 (granted)
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Force transducer for electronic devices
J.C. Doll, P.O. Gupta, T. Songatikamas, A.J. Monkowski
US20180314331A1 (granted)
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Piezo-actuated MEMS resonator with surface electrodes
J.C. Doll, P.M. Hagelin, G.C. Hill, N. Miller, C.I. Grosjean
US20180226942A1 (granted)
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Electronic device including movable magnet based actuator for deforming a display and related methods
J.C. Doll, T. Songatikamas, A.J. Monkowski, P.O. Gupta
US9949390B1 (granted)
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Integrated gap sensing electromagnetic reluctance actuator
T. Songatikamas, J.C. Doll, M.A. Bigarani
US20180090253A1 (application)
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Multi-core, multi-dimension electromagnet
T. Songatikamas, J.C. Doll, M.A. Bigarani
US20180085786A1 (granted)
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Microelectromechanical resonator
J.C. Doll, N. Miller, C.I. Grosjean, P.M. Hagelin, G.C. Hill
US9712128B2 (granted)
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Temperature-engineered MEMS resonator
J.C. Doll, P.M. Hagelin, G.C. Hill, N. Miller, C.I. Grosjean
US9705470B1 (granted)
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Temperature insensitive resonant elements and oscillators and methods of designing and manufacturing same
R.M. Berger, G.C. Hill, P.M. Hagelin, C.I. Grosjean, A. Partridge, J.C. Doll, M. Lutz
US9695036B1 (granted)
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Rise time reduction of thermal actuators operated in air and water through optimized pre-shaped open-loop driving
(pdf)
T. Larsen, J.C. Doll, F. Loizeau, N. Hosseini, A.W. Peng, G.E. Fantner, A.J. Ricci, B.L. Pruitt
Journal of Micromechanics and Microengineering, Vol. 27, No. 4, 2017.
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A MEMS-assisted temperature sensor with 20 uK resolution, conversion Rate of 200 S/s, and FOM of 0.04 pJ/K2
(pdf)
M. Heidarpour Roshan, S. Zali Asl, K. Joo, K. Souri, R. Palwai, W. Chen, A. Singh, S. Pamarti, N. Miller,
J.C. Doll, C. Arft, S. Tabatabaei, C. Sechen, A. Partridge, V. Menon
IEEE Journal of Solid-State Circuits, November 2016.
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Nanomechanical Actuation of a Silicon Cantilever Using an Azo Dye, Self-Assembled Monolayer
(pdf)
A. Joseph Rastegar, M. Vosgueritchian, J.C. Doll, J.R. Mallon, B.L. Pruitt
Langmuir, Vol. 29, No. 23, 2013.
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Faster than the Speed of Hearing: Nanomechanical Force Probes Enable the Electromechanical Observation of Cochlear Hair Cells
(pdf)
J.C. Doll, A.W. Peng, A.J. Ricci, B.L. Pruitt
Nano Letters, Vol. 12, No. 12, 2012.
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High bandwidth piezoresistive force probes with integrated thermal actuation
(pdf)
J.C. Doll, B.L. Pruitt
Journal of Micromechanics and Microengineering, Vol. 22, No. 9, 2012.
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DEG/ENaC but Not TRP Channels Arethe Major Mechanoelectrical Transduction Channels in a C. elegans Nociceptor
(pdf)
S.L. Geffeney, J.G. Cueva, D.A. Glauser, J.C. Doll, T.H.-C. Lee, M. Montoya, S. Karania, A. Garakani, B.L. Pruitt, M.B. Goodman
Neuron, Vol. 71, Issue 5, 2011.
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Patterned cracks improve yield in the release of compliant microdevices from silicon-on-insulator wafers
(pdf)
G.C. Hill, J.I. Padovani, J.C. Doll, B.W. Chui, D. Rugar, H.J. Mamin, N. Harjee, B.L. Pruitt
Journal of Micromechanics and Microengineering, Vol. 21, No. 8, 2011.
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Self-heating in piezoresistive cantilevers
(pdf)
J.C. Doll, E.A. Corbin, W.P. King, B.L. Pruitt
Applied Physics Letters, 98, 223103 (2011).
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Role of surface roughness in hysteresis during adhesive elastic contact
(pdf)
H.K. Kesari, J.C. Doll, B.L. Pruitt, W. Cai, A.J. Lew
Philosophical Magazine Letters, 2010.
Recognized as a highly commended paper of 2010.
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Design of Piezoresistive vs. Piezoelectric Contact Mode Scanning Probes
(pdf)
J.C. Doll, B.L. Pruitt
Journal of Micromechanics and Microengineering, 20, 095023, 2010.
Chosen as one of the highlight papers of 2010.
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Aluminum nitride on titanium for CMOS compatible piezoelectric transducers
(pdf)
J.C. Doll, B.C. Petzold, B. Ninan, R. Mullapudi, B.L. Pruitt
Journal of Micromechanics and Microengineering, 20, 025008, Feb. 2010.
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Piezoresistive cantilever performance, part II: optimization
(pdf)
S.-J. Park, J.C. Doll, A.J. Rastegar, B.L. Pruitt
Journal of Microelectromechanical Systems, Vol. 19, No. 1, pp. 149 - 161, Feb. 2010.
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Piezoresistive cantilever performance, part I: analytical model for sensitivity
(pdf)
S.-J. Park, J.C. Doll, B.L. Pruitt
Journal of Microelectromechanical Systems, Vol. 19, No. 1, pp. 137 - 148, Feb. 2010.
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Design optimization of piezoresistive cantilevers for force
sensing in air and water
(pdf)
J.C. Doll, S.-J. Park, B.L. Pruitt
Journal of Applied Physics, Vol. 106, Issue 6, pp 064310, September 2009.
Also selected for the Virtual Journal of Nanoscale Science & Technology.
Open source Matlab code for cantilever design optimization
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SU-8 Force Sensing Pillar Arrays for Biological Measurements
(pdf)
J.C. Doll, N. Harjee, N. Klejwa, R. Kwon, S. Coulthard, B.C. Petzold, M.B. Goodman, B.L. Pruitt
Lab on a Chip, Vol. 9, pp 1449-1454, May 2009.
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The phenomenon of twisted growth: Humeral torsion in dominant arms of high performance tennis players
(pdf)
R.E. Taylor, C. Zheng, R.P. Jackson, J.C. Doll, J.C. Chen, K.R.S. Holzbaur, T. Besier, E. Kuhl
Computer Methods in Biomechanics and Biomedical Engineering, Volume 12, Number 1, February 2009.
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Artificial dirt: Microfluidic substrates for nematode neurobiology and behavior
(pdf)
S. Lockery, K. Lawton, J.C. Doll, S. Faumont, S.M. Coulthard, T.R. Thiele, N. Chronis, K.E. McCormick, M.B. Goodman, B.L. Pruitt
J Neurophysiol, Vol. 99, No. 6, pp. 3136-43, Jun 2008.
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High-speed multispectral imaging of nanoplasmonic array
(pdf)
G.L. Liu, J.C. Doll, L.P. Lee.
Optics Express, 13, 8520-8525, October 2005.
- Magnetic Nanocrescents as Controllable Surface-Enhanced Raman Scattering Nanoprobes for Biomolecular Imaging
(pdf)
G.L. Liu, Y. Lu, J. Kim, J.C. Doll, L.P. Lee.
Advanced Materials, 17, 2683-2688. August 2005.
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Dual-MEMS-Resonator Temperature-to-Digital Converter with 40uK Resolution and FOM of 0.12 pJ/K2(pdf)
M. Heidarpour Roshan, S. Zali Asl, K. Joo, K. Souri, R. Palwai, W. Chen, S. Pamarti, J.C. Doll,
N. Miller, C. Arft, S. Tabatabaei, C. Sechen, A. Partridge, V. Menon
Proceedings of ISSCC, February 2016.
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25x Rise Time Reduction in Thermal Acuation Enabled by the Use of Pre-Shaped Input Signals
T. Larsen, J.C. Doll, F. Loizeau, N. Hosseini, G. Fantner, and B.L. Pruitt
Nanomechanical Cantilever Workshop, Auckland, New Zealand, July 2015.
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Ultra-Thin Atomic Layer Deposition Films for Corrosion Resistance
A.J. Haemmerli, J.C. Doll, J. Provine, R.T. Howe, B.L. Pruitt
Proceedings of Transducers, Barcelona, June 2013.
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Real-Time Force Measurement of Cell-Generated Forces During Bacterial Phagocytosis
J. Moeller, J.C. Doll, M.A. Hopcroft, E.A. Mazzochette, K-W. Jung, V. Vogel, B.L. Pruitt
Microtechnologies in Medicine and Biology, Marina del Rey, California, April 2013.
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Microsystems and Functional Assay for Mechanobiology
B.L. Pruitt, J.C. Doll, S.J. Park, N. Harjee, B.C. Petzold
Proceedings of Transducers, Barcelona, June 2013.
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MEMS Force Probes for Cell Mechanobiology at the Microsecond Scale
J.C. Doll, B.L. Pruitt
Hilton Head Workshop, 2012.
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Piezoresistive Cantilevers for Biological Force Measurements
J.C. Doll, S.-J. Park, N. Harjee, B.C. Petzold, B.L. Pruitt
Nanomechanical Cantilever Workshop, Mumbai, India, 2012.
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The study of activation kinetics in the mammalian auditory system
A. Peng, J.C Doll, A. Ricci
Association for Research in Otolaryngology MidWinter Meeting, San Diego, CA, 2011.
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New devices for investigating hair cell mechanical properties
J.C Doll, A. Peng, A. Ricci, B.L. Pruitt
Mechanics of Hearing Workshop, Williamstown, MA, 2011.
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Optomechanical modulation of azobenzene-coated cantilevers
A.J. Rastegar, Y. Gao, J. Mallon, Y. Qu, J.C. Doll, B.L. Pruitt
Nanomechanical Cantilever Workshop, Dublin, Ireland, 2011.
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Patterned cracks in the buried oxide layer to improve yield in device release from SOI wafers
G.C. Hill, J.I. Padovani, B.W. Chui, H.J. Mamin, D. Rugar, N. Harjee, J.C. Doll, B.L. Pruitt
Proceedings of MEMS, Cancun, Mexico, 2011.
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Optimization with Process Limits and Application Requirements for Force Sensors
S.-J. Park, J.C. Doll, N. Harjee, B.L. Pruitt
IEEE Sensors Conference, Hawaii, 2010.
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Surface Roughness Induced Hysteresis in Adhesive Elastic Contacts
H. Kesari, J.C. Doll, W. Cai, B.L. Pruitt, A.J. Lew
U.S. National Congress of Theoretical and Applied Mechanics, Penn State, 2010.
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Design of Piezoresistive vs. Piezoelectric Contact Mode Scanning Probes
J.C. Doll and B.L. Pruitt
Open poster at Hilton Head Workshop, 2010.
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Piezoresistive cantilevers optimized for kilohertz force sensing in aqueous solutions
J.C. Doll, B.C. Petzold, M.B. Goodman, B.L. Pruitt
Nanomechanical Cantilever Workshop, Banff, 2010.
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Coaxial tip piezoresistive scanning probes for high-resolution electrical imaging
N. Harjee, A.G.F. Garcia, M. Konig, J.C. Doll, D. Goldhaber-Gordon, B.L. Pruitt
Proceedings of MEMS, Hong Kong SAR, China, pp.344-347, 2010.
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Piezoresistive Cantilever Optimization and Applications
J.C. Doll, S.-J. Park, N. Harjee, A.J. Rastegar, J.R. Mallon, B.C. Petzold, G.C. Hill, A.A. Barlian, B.L. Pruitt
Materials Research Society Fall Meeting, invited paper, 2009.
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A High d33 CMOS Compatible Process for Aluminum Nitride on Titanium
J.C. Doll, B.C. Petzold, B. Ninan, R. Mullapudi, B.L. Pruitt
Proceedings of Transducers, Denver, June 2009.
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High Frequency Force Sensing with Piezoresistive Cantilevers
J.C. Doll, B.C. Petzold, P. Ghale, M.B. Goodman, B.L. Pruitt
Proceedings of Transducers, Denver, June 2009.
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Measuring Thresholds for Touch Sensation in C. elegans
J.C. Doll, S. Muntwyler, F. Beyeler, S. Geffeney, M.B. Goodman, B.J. Nelson, B.L. Pruitt
Microtechnologies in Medicine and Biology, Quebec, April 2009.
Best Abstract Award
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Contact Mechanics between Rough Adhesive Surfaces
H. Kesari, J.C. Doll, W. Cai, B.L. Pruitt, A.J. Lew
Adhesion Society Meeting, Savannah, GA, February 2009.
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Exploring Cellular Tensegrity: Physical Modeling and Computational Simulation
C.H. Zheng, J.C. Doll, E. Gu et al.
ASME Summer Bioengineering Conference, 2008.
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Biological Measurements of C. elegans Touch Sensitivity with Microfabricated Force Sensors
J.C. Doll, N. Harjee, N. Klejwa, R. Kwon, S. Coulthard, M. Goodman, B. Pruitt
Proceedings of MicroTAS, 2007.
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Molecular Engineering of Smart Protein Scaffolds for Cardiac Stem Cell Differentiation
J. Blundo, O. Abilez, K. Straley, J.C. Doll, F. Cao, J. Wu, C. Zarins, S. Heilshorn, B.L. Pruitt
Materials Research Society Fall Meeting, 2007.