Dr. Andy Hoffer

Professor of Biomedical Physiology and Kinesiology
Director, Neurokinesiology Laboratory


Bachiller Engineering IAVA Montevideo

BS Physics Harvey Mudd College

PhD Biophysics Johns Hopkins University

Phone: (778) 782-3141


Dr. Andy Hoffer was born in Montevideo, Uruguay where he studied engineering. Upon receiving scholarships to study in the USA, he obtained a B.S. in physics in 1970 from Harvey Mudd College and a Ph.D. in biophysics in 1975 from Johns Hopkins University. He then came to Canada for postdoctoral training at the University of Alberta, Faculty of Medicine until 1978, when he joined the Laboratory of Neural Control, U.S. National Institutes of Health, as Staff Fellow. In 1982 he returned to Canada as assistant professor and Alberta Heritage Scholar at the University of Calgary, Faculty of Medicine, where he became a full professor. In 1991 he moved to Simon Fraser University as professor and director of the School of Kinesiology (until 1997) and he is currently professor of Biomedical Physiology and Kinesiology in the Faculty of Science. Dr. Hoffer founded three biotechnology companies spun out from his SFU laboratory:  Neurostream Technologies in 1998, Bionic Power in 2006 and Lungpacer Medical in 2009.

Research Summary

Beginning with the development of implantable nerve cuff recording electrodes during his doctoral thesis, Dr. Hoffer’s core research has addressed:

  • How peripheral sensory and motor neurons function during voluntary movements, and
  • development of assistive devices for functional rehabilitation of people affected by paralysis after brain or spinal cord injuries, limb amputations, and other neurological or neuromuscular disorders.

During the past 30 years, the SFU Neurokinesiology Laboratory and its 3 spun-out startup companies, research trainees and collaborators created uniquely specialized facilities, techniques and protocols for:

  • neurophysiological and biomechanical recordings during unrestrained voluntary movements, and
  • invention, design, prototyping, testing, and pre-clinical validation of neuroprosthetic and neuroassistive solutions for people with neurological, neuromuscular or sensory impairments.

Research Themes

Nerve Cuff Electrodes for Research and Clinical Uses
Doctoral Thesis at Johns Hopkins University

For his PhD thesis supervised by W.B. Marks, Andy Hoffer designed and built nerve cuffs and low-noise amplifiers that recorded μVolt-level peripheral nerve activity during locomotion. Tripolar cuffs implanted in rabbit hindlimb nerves provided the first-ever recordings of sensory firing patterns in intact animals.

Nerve fiber activity during normal movements

JA Hoffer, WB Marks, WZ Rymer. Soc Neurosci Abst 4:300, 1974.


Postdoctoral Research at U. Alberta

Richard B. Stein’s supervision at U. of Alberta, Andy Hoffer and colleagues implanted nerve cuffs to track the survival of motor and sensory nerve fibers after peripheral nerve lesions. They subsequently pioneered new methods to assist upper limb amputees to control powered prosthetic limbs.  

Compound action potentials recorded from mammalian peripheral nerves following ligation or resuturing.

LA Davis, T Gordon, JA Hoffer, J Jhamandas, RB Stein. Journal of physiology 285 (1), 543-559, 1978.


Differential atrophy of sensory and motor fibers following section of cat peripheral nerves

JA Hoffer, RB Stein, T Gordon. Brain research 178 (2-3), 347-361, 1979


Long‐term effects of axotomy on neural activity during cat locomotion.

T Gordon, JA Hoffer, J Jhamandas, RB Stein.  The Journal of Physiology 303 (1), 243-263


New approaches to controlling powered arm prostheses, particularly by high-level amputees.

RB Stein, D Charles,  JA Hoffer, J Arsenault, LA Davis, S Moorman, B Moss.  Bull. Prosth. Res. 17: 51-62, 1980.



Andy Hoffer and fellow PDF Steen Andreassen collaborated in studies to quantify stretch reflex stiffness vs. intrinsic muscle stiffness, motivated by invaluable mentorship from T. Richard Nichols while he was also a PDF training in Stein’s lab

Regulation of soleus muscle stiffness in premammillary cats: intrinsic and reflex components.

JA Hoffer, S Andreassen. Journal of neurophysiology 45 (2), 267-285, 1981.



Staff Fellowship at the Laboratory of Neural Control, NIH

In 1978, Andy Hoffer joined the NIH Lab of Neural Control in Bethesda, MD as Staff Fellow and collaborated with Gerald Loeb to equip a unique facility where they recorded in behaving animals the activity from single neurons with floating fine-wire ”hatpin” microelectrodes as well as implanted nerve cuffs, EMG electrodes, tendon force and muscle length transducers, described in a Science paper and seven J Neurophysiol papers (spindles 1, 2, 3 and motoneurons 1, 2, 3, 4).

Discharge patterns of hindlimb motoneurons during normal cat locomotion

JA Hoffer, MJ O'Donovan, CA Pratt, GE Loeb.  Science 213 (4506), 466-467. 1981.



Targeted Reinnervation of Nerve Stumps in Amputees

In an Ann Biomed Eng 1980 paper, Hoffer and Loeb analyzed the potential for long-term clinical uses of the five implanted technologies. Of these, neurograms recorded from intact nerves by cuff electrodes were the most likely to remain stable over many months and years.

In amputees, however, cut motor axons atrophy, and their signals become too small to record reliably. Hoffer and Loeb introduced the concept of “targeted reinnervation”: graft the nerve stumps onto donor muscles. This idea was later put into practice by Todd Kuiken and now provides amputees with enhanced motor signals to control prostheses.

Implantable electrical and mechanical interfaces with nerve and muscle

JA Hoffer, GE Loeb.  Annals of biomedical engineering 8 (4), 351-360, 1980.


Professor and Alberta Heritage Fellow at U. Calgary

In 1982 Andy Hoffer took a faculty position at the University of Calgary where, with an Alberta Heritage Medical Research Establishment grant, he built a chronic recording lab and continued using and refining implantable sensing technologies jointly developed at NIH. With grants from MRC, NCE, Rick Hansen and U.S. Spinal Cord Research Foundation he attracted excellent trainees, including Angel Caputi with whom the Calgary team pioneered the capability to record muscle fiber length changes in intact animals using ultrasound transit-time; Thomas Sinkjær, with whom they compared muscle stiffness and reflex properties in intact and decerebrated animals, and Morten Haugland, whose thesis described properties of sensory afferent signals recorded from peripheral nerves in response to skin contact forces.  Hoffer was also granted his first US patent while in Calgary, for a nerve-cuff based invention.

Closed-loop, implanted-sensor, functional electrical stimulation system for partial restoration of motor functions

JA Hoffer.  US Patent 4,750,499, 1988.


Roles of muscle activity and load on the relationship between muscle spindle length and whole muscle length in the freely walking cat   

JA Hoffer, AA Caputi, IE Pose, RI Griffiths.  Progress in brain research 80, 75-85, 1989.


Factors determining segmental reflex action in normal and decerebrate cats

T Sinkjær, JA Hoffer. Journal of neurophysiology 64 (5), 1625-1635, 1990.


Techniques to study spinal-cord, peripheral nerve, and muscle activity in freely moving animals         

JA Hoffer.  Neurophysiological Techniques, 65-145, 1990.


Skin contact force information in sensory nerve signals recorded by implanted cuff electrodes

MK Haugland, JA Hoffer, T Sinkjær. IEEE Transactions on Rehabilitation Engineering 2 (1), 18-28, 1994.


Slip information provided by nerve cuff signals: application in closed-loop control of functional electrical stimulation

MK Haugland, JA Hoffer. IEEE Transactions on Rehabilitation Engineering 2 (1), 29-36, 1994.


Artifact-free sensory nerve signals obtained from cuff electrodes during functional electrical stimulation of nearby muscles

MK Haugland, JA Hoffer. IEEE Transactions on Rehabilitation Engineering 2 (1), 37-40., 1994.



Professor and Director of the Neurokinesiology Laboratory at Simon Fraser University

In 1991 Hoffer took a continuing faculty position at SFU, where he also served as the Director of the School of Kinesiology until 1997.  He moved most of his Calgary lab equipment, several team members and MRC and NCE funds to SFU, and in 1992 was awarded a large research contract by the NIH/NINDS Neural Prosthesis Program to develop laser-based methods to fabricate advanced nerve cuff electrodes and to demonstrate their long-term stability, safety and efficacy in pre-clinical trials in animals. This research resulted in several publications and patents, including:

Implantable cuff having improved closure

K Kallesoe, JA Hoffer, K Strange, I Valenzuela. US Patent 5,487,756, 1996.


Nerve cuff having one or more isolated chambers

JA Hoffer, Y Chen, KD Strange, PR Christensen. US Patent 5,824,027, 1998.


Restoration of use of paralyzed limb muscles using sensory nerve signals for state control of FES-assisted walking

KD Strange, JA Hoffer. IEEE Transactions on Rehabilitation Engineering 7 (3), 289-300, 1999.


Fully implantable nerve signal sensing and stimulation device and method for treating foot drop and other neurological disorders

M Baru, JA Hoffer, E Calderon, GB Jenne, A Calderon. US Patent 7,636,602, 2009.


Neural signals for command control and feedback in functional neuromuscular stimulation: a review

JA Hoffer, RB Stein, MK Haugland, T Sinkjaer, WK Durfee, AB Schwartz. J Rehabil Res Dev 33 (2), 145-157, 1996.


Nerve cuff, method and apparatus for manufacturing same

JA Hoffer, MO Imbeau, JM Vallieres.  US Patent 8,214,056, 2012.